None of the stuff about the GSINR or the Corp Court applies, as far as I can see. As you mentioned further up the quote above, all the SIN information is also held by the issuing corp, and I am specifically talking about AA/AAA corps and their employees here. So all that data can be at their fingertips, if they want it to be.
Sadly it does apply. GSINR is controlled by the corporate Court. They dictate what is stored on the SIN, how it is stored, what is included in the SIN and what is omitted. While Renraku may maintain their own SIN registry, they still have to comply with the standards set by the corporate court, or risk losing access to the GSINR and be solely reliant on their own network.
And considering the topographic framework of the interconnected Matrix, and the vast role that SINs play in commerce in the 2070s+, that is not feasible.
Think of it like the Google/Apple Store Terms of Service. You can use their Store fronts to sell and buy anyone peoducts, but if you break the TOS, you are removed... SAme thing here. If you don't comply to the GSINR, you lose access to it... And that is not something any one can afford.
The two major other reasons are Time and Security.
Time We have no idea how long it takes to run a informatics search in the GSINR. All that we do know is that the higher the rating of the scanner, the better the scan, and the longer it takes. We know that running a "deep scan" at a police station (rating 6+) takes hours.
So, does asking for a finger print informatics return take 1 second? Or 1 hour?
If its a second, great...
If its 30 seconds... that's a LOT of lost productivity over the course of a year when you factor in everyone....
If its 1 minute... well... now your system is fallen apart as no one is going to use it on the ground level and will be defeated by the users.
("Don't let that fucking door close!!! I am not standing here for a gawddamn minute while 'IT' figures out I'm me! I have to Piss NOW!!!")
This is something we just can't answer. But we can guess at that its "longer than near instant"
SecurityThe GSINR undergoes BILLIONS of additions, edits, changes, corrections, and modification every second, as ownership and currency exchanges hands around the world. Which means the Renraku database also undergoes BILLIONS of additions, edits, changes, corrections, and modifications every second as it keeps as current as it can tot he changing wealth and infrastructure of the world.
THAT is not secure.
Add to the fact, that the Registry is also under the direct control of separate entity (the CC), who have ownership level control over the system. The Grey and Black markets that seem to have access to the registry to the level of being able to inact ownership level control (Rating 6 fake SINs)...
Its looking more and more like the vaunted "security" of the GSINR is not so great.... (OR, that event eh best system has holes...)
So basically, we have several dozen players (the CC, AA/AAA Corps, National Governments, Grey/Black market players) all who can "play" with the registry. (And the thousands of people this actually works out to be. Bureaucracy is a wonderful thing.)
How is that sounding more secure then a privately maintained card reader/Fob/bio scan?
you have the building you want protected. So you install an in house server(host) to handle the security devices. you have one point (ok, in the matrix world not so much) of entry for information (the in house server/host). All checks are handled on a simple Pass/fail between the device and the host, instead of relying on the device, to the GSINR to the host.
Now, you only have a single host to protect your security system, and thus one place to look when a breach happens, instead of relying on a correct response from a known (security wise) compromised datastore and then relying on said compromised datastore to begin recovery.
In short,
From a security stand point, there are too many "fingers in the Pie" to rely on the GSINR as a security tool for the efficiency of daily security, as there are too many who could make catastrophic changes on a whim...
<Anyone else remember Big D's Will?>
the other question I have for you however....
"What happens when the GSINR returns a false negative?"
They happen... Most thumb scanners won't read the thumbs of people "who actually work for a living"

(by that, I mean most people in construction, yard workers, factory workers. Because we work with our hands on a daily basis with rough abrasive surfaces, our finger prints get worn right off, or get calloused over.)