So basically this is an area of the SR metaverse that needs to be fleshed out. To break it down to Barney-level:
-Yes, the megacorps are going to buy influence that will enact legislation to regulate competition.
-The corps are, above all other concerns, in business to sell products to consumers; whether those consumers are private citizens, gov't agencies, or other corps. Sure, the megacorps essentially force their workers to buy everything from them, but in fact, a corp cannot grow this way nor can it sustain itself by this alone. Businesses MUST grow and adapt, or they will lose their market shares to new and upcoming businesses.
-Selling product is tough when your consumers can't afford to buy your product. In SR we focus a lot on the bottom-end of the food chain, because it's easier to hide there, and we spent all our resources on wired reflexes and muscle replacements (or magic priority). But in-fact. In order for this metaworld to function,there must be a healthy class of people with disposable income; and we cannot forget that shadowrunners really make up less than 1% of the population.
-There must be some sort of stable law enacted in order for businesses to grow to the point they have in the SR universe, especially when you consider the mass casualty events in the SR timeline.
-Extraterritoriality, while a huge deal for the corps themselves, and their employees, is a relatively small piece of the overall pie as far as nations are concerned. It allows corps to police their own property and do with it as they wish; but, there is still law that they must abide (or appear to abide) by, enforced by governments. If not, the whole house of cards falls down when people do what they want to do. LS and KE cannot police everyone.
-Cynicism says that when a corp gets caught with their hands in the jar, so to speak, all they would have to do is pull strings, deploy lawyers, and buy influence. Problem is, there are thousands of other corps doing the same thing, waiting to eliminate competition.
-If a corp is caught in a crime:
- They risk losing their bottom line and the ability to move product.
- They risk lawsuits.
- They risk law enforcement coming in and shutting them down.
- They risk prison time.
So in other words, there must be a power to write and enforce laws, provide security and a stable business environment; and be a ruling body beyond just a massive proxy tax collection agency for the corporations.
Just my .02.