See I'm not so sure about that specifically because they are corporations and want the highest bottom line they can get. Yes you can rule through fear but history shows those kind of regimes run into problems due to the limitations they put on people. Something that would be made worse in the heavily globalised world of Shadowrun with the most productive and valuable members needing by their very nature to have access to the rest of the world. Doctors, lawyers, scientists and many others all need access to the rest of the world's developments in order to get the most out of them and they'll have interactions with Corp citizens who aren't as valuable. Similarly a happy, productive worker is one who'll put the unpaid overtime in out of a sense of competitiveness and a desire to look good to the bosses anyway whereas an unhappy one will head home as soon as their hours are done.
You are assuming there is such a thing as overtime.
Currently in Thailand, the standard wage is 300 Baht for a 10 hour day. (just over $9 US a day). with no clause for overtime pay
Once again, you are forgetting that SR is not our world. The social safety nets you grew up with a LONG gone. There is no welfare, there is no universal healthcare, there is no old age pension, there is no government run assistance programs. You sink or swim by your own merits and what you can scrape together. Or you work for a Corp and take what they give you.
Some professions will be paid more, some will be paid less. But even today, many lawyers don't make as much as people think they do thanks to the huge amount of Lawyers that are being pumped out of universities today. At UVic (University of Victoria), there are 300 new lawyers graduating every year. And that has been going on for 40 years since my father graduated from there with a Law degree.
In SR, only the very best lawyers would find themselves in Corp Enclaves and "safe". The rest are just other wage slaves doing the work as required.
Could a corporation issue corporate script, indentured slavery or revoke your citizenship for being unproductive? Yes without a doubt but why would they use such heavy handed techniques when there are other better options.
Because they can. And they know they will get the money back from their employees, while limiting those said employees from buying competitors' merchandise. In short they turn their own employees into guaranteed sales for their products, thus ensuring they ALWAYS have a marketplace advantage over everyone else with a select number of consumers. This is exactly why even today some companies print their own "funny money" that they had out to customers. For example: Canadian Tire. With every purchase at Canadian Tire, you get $0.01 Canadian Tire Dollars for every $1 you spend. the Customer can save up these CTDs and then use them for a purchase later on. They have absolutely NO value to any other business, or bank, but can be spent like real money at any Canadian Tire store in Canada (and ONLY Canadian Tire!). By giving out the CTDs, Canadian Tire is ensuring that some people will always shop there as they are getting a "discount" on things thanks to the CTD program...
And that is not including the real world examples of this very thing from history, as many businesses back in the 1700 to 1800s did this very thing as well. "I sold my soul to the company store" isn't just a line from a song, but actually a historic fact of the gross injustices many businesses did to their employees back in the day. (along with actually chaining employees to their work stations. 80 hour work weeks, enforced housing sleeping 15 to a room, and other barbaric practices that we world find abhorrent today, but were common place back then)
So Johnny the slacker is a corporate citizen and isn't producing anything why take away his citizenship when you can simply balance healthy care and other "services" so that there's an incentive to pay your way. Especially when setting the precedent for "we can take this off you" could backfire by making valuable citizens nervous.
Because he produces nothing, is a drain on the system and sucks up Corporate profits just by being a "drag" on the system. By cutting him loose and revoking his citizenship, they SAVE that money.
Free health care ensures you don't spread a dangerous disease to others. 200 nuyen a month gets you proper treatment, 500 gets you good treatment, 1000 gets you optionals like dental and optical and so on. Unions as said are controlled and guided.
First off: "free Healthcare" isn't FREE! Never has been, never will be. You pay for it in your taxes, which is why countries with "free" healthcare have THE highest personal income taxes in the world! Take Canada, my home country.
"In 2016, total health expenditure in Canada is expected to reach $228 billion, or $6,299 per person. It is anticipated that, overall, health spending will represent 11% of Canada’s gross domestic product (GDP)."
https://www.cihi.ca/en/health-spending
That's $228 BILLION for a country of under 37 million people. And is why my Federal income tax rate is 43% of my Income. Not to mention my 18.5% Provincial Income Tax that I owe to the province I live in. AND THEN there is the $175/month Fair Care Health Plan I MUST pay every month with no option to opt out of. I still have to pay 100% of all drug, dental, and Optical costs out of pocket.
So really, what do I get for my 61% income tax paid to the respective governments? Not much since 40,000 citizens (including myself!) in my home town alone do not have a family doctor, thanks the Doctor shortage across the country. So I say it again, "Free Heathcare is a Myth"
Everyone uses the Nuyen but our Corp has lower costs for Corp produced products vs external ones vs other corporate ones. Say cost to produce + 20/50/75 respectively.
The Nuyen is the standard that ZOGB uses, much like how the US dollar is used today to measure the economic output of every country, even though they do not use US dollars. IT doesn't stop a company from using their own script. And in fact, ALL the big 10 do use their own script for the reasons I listed above.
The very fact their corporate citizenship is so low argues against them pushing their people too far because an indentured mage or worse one who sees their non magical kids/friends being forced into indentured servitude is a mage who's ripe for an extraction target and they'll definately have some interaction with non-corp citizens.
Actually the opposite. The fact the numbers are so slow points to it being a very exclusive club. And the reason for that is that citizens cost money. There has to be a reward/benefit to being a Corporate Citizen, otherwise no one would bother to try to become one. Those benefits are probably the very things you are taking for granted and assuming everyone has. (remember that there was a world wide government collapse in SR, so many things you take for granted are GONE!)
It's probably little things, Like having a roof over your head that isn't falling apart. Electricity on demand, instead of when it rationed to your block. Relative safety of a Corporate Enclave instead of having to dealing with roving street and biker gangs. Access to a Doctor when you need one what offers more then just clinic services. A Pension! Access to food from the Corporate store instead of standing in line for Soy products at the corner store. Hot, clean water!
But of course, all these things cost money. There is the infrastructure that has to be built for all of it. That infrastructure has to be maintained. Which comes out of the Corp's bottom line. The more people you offer these services to, the more it costs to maintain. The more it costs , the more it hurts the Corp Pocket book.
This is one of the reasons why Corporations didn't just take over the world when the governments collapsed one by one. Ruling the world directly hurts profits. Much better to get the Governments to pay for all the expensive stuff like heating, sanitation, water, infrastructure, housing, healthcare, pensions, and the hundreds of other things needed to run a country and just charge the governments to build them through construction companies, and waste removal services. (which are paid for by a Country's citizens through their taxes)
On the other hand if you don't take away citizenship except for crimes against the corporation that can be justified to the sheeple but limit it's awarding to the most valuable, special acquisitions and an occasional lucky lottery winner you get as seen here a much lower number of corporate citizens.
It's also supports by the sins system with a limited vs full corporate sin. Limited would like you said be awarded/removed fairly regularly a mage coming to work for Renraku would probably get limited citizenship for the duration of their employment then have it revoked, but a janitor who was born to full corporate citizenship would have their citizenship for life even if they were constantly bring held up to society as a shameful example of someone who had all the breaks and blew it. Which in itself is an effective method of control why take away their sin when you can socially shame them while simultaneously holding them up as an example of how you "only take away full citizenship if they commit crimes".
Because once again with that citizenship comes certain rights and privileges, which cost money to the Corp at best. Or their Reputation at worst (as for a Corp, a hit to their reputation can cost them MILLIONS, even a short term loss of face.)
For example. They have a Corp Employee that is a total slacker and doesn't produce anything meaningful to the company. Worse still he is a substance abuser. One day this employee is driving to work stoned, loses control of his Car and slams into a bus of schoolkids, killing them all. The Corp is going to take a public relations hit for the actions of this now dead employee, which could cost them millions in lost sales until the tied of anger blows over. Not to mention the lawsuits from the families of the Kids, regardless if they win or not.
Far better in the cost/benefit analysis to cut the underproductive employee loose then continuing to let him drag the company down.
Just like Today, Citizens expect their Country/Corp to be there for them in rough times, and to protect them from other countries laws and rules when problems break out. They expect their country to look after them. And in some cases feed, house, educate, nurture and support them.
(Whatever happened to: "Ask not what your country can do you for, but what YOU can do for your Country!"

That famous line is only 60 years old...)
Once again, Corps are not countries. They do not act like countries, they do not think like countries. They are businesses and act like Businesses. If you do not increase the bottom line of a business, you are let go right away. And if you don't increase the bottom line in some measurable, distinct way you will probably never become a Citizen for that Corp, as Citizens have a built in cost to them, which has to be met or exceeded before their is a reason for a Corp to even offer the rewards of Citizenship to you.