Ah, but in the USA, there was a long-standing distrust of centralized databases of all sorts. My impression is that in recent decades this has mostly fizzled, but e.g., one of the objections to the original Social Security Act was its assignment of a unique number to every eligible individual. And we still have *separate* databases for voting, for taxes, for driver's licenses, for passports, for birth/death/marriage, and so on and so forth. (Mostly maintained by totally separate government agencies. E.g., I think I'm registered to vote in two different counties, because I never bothered to unregister when I moved, and they don't really check the lists against each other.)
Oh, and IIRC it's pretty much legal to just make up the name you want to use when registering for these databases.
The USA's ways of doing things are all very... historically contingent.