Ok. So you have me on one thing: it wasn't originally intended to be used as a personal identifier. You learn something new every day.
But then according to your very own link, it has universally been used and repurposed for this exact thing for the last 45 years, without issues, and with duplicate SSNs no longer being a problem.
I'd say that sounds like a very proven form of identification. So what problem do you (OP / ams6110) have with people using it as such?
> So what problem do you (OP / ams6110) have with people using it as such?
A SSN is the "secret" bit to a small amount of otherwise-public info (name, address, some other bits) to getting a loan or credit card or other credit-related actions in my name.
I went to a small two-year school that used SSNs as their personal identifier numbers. Someone broke in and stole student records. Now the school's poor identity choices has put thousands of students' financial identities at risk.
One problem with using an SSN as a identifier is that the number exists for the administration of the Social Security system, so only people who pay into or will receive money from the system are eligible for a number.
Not everyone in the US is eligible for an SSN (e.g., some non-residents living in the US). When I first came to the US as a student, I had difficulty doing things like signing up for a credit card or a cellphone for this reason.
There are other numbers that systems sometimes but do not consistently accept, for instance an ITIN, which is the tax ID number the IRS will issue you if you aren't eligible for a SSN.
Correct me if I'm wrong, but I presumed that was its one stated purpose?