I suppose I can see your point, but understand that it's a matter of development anyhow. The amount of data that has to be developed for a Rating 4 SIN includes the amount of data that has to be developed for a Rating 3 SIN. Increasing a L3 to an L4 starts from the established L3, instead of starting from scratch, is all.
Not necessarily.
IIRC, some of what goes into creating a fake is also not just electronic data but also actual time, properly aged physical documents.
Like having a Birth Certificate that is from someone the same age as you "roughly".
Then having an actual drivers license that is 16 years younger than the birth certificate, and copies of it on file at several different DMVs.
Not just electronic data, or forgeries, that is the lower end stuff, but the really good id's were not created on the fly but were "grown" over the years.
So your "ID-Maker" also had his Niece go in & get that drivers license using that birth certificate from a baby that died shortly after being born.
Then the ID-Maker faithfully renewing it every 4 years. Putting in Changes of address for a college town at age 20, etc etc.
To me those are what the L6 id's involve. Well, at least that is the cool stuff you see watching nifty spy movies & such, etc etc.
In 2070 I can only imagine that it is even more involved. Having to match a good fake SIN would mean some serious genetic data I would think.
Add in the thought about all the data that is being collected about you by marketing, IIRC there was a line about RFID sized cameras on soda cans looking for reactions from people as they drink the soda, or something like that. I don't want to even think the shear amount of data that is out there to be cross referenced by some corp super computer or really dedicated NSA hacker etc etc.