[clairity]

UUIDs are a terrible idea, as you're completely ignoring the UX of SSNs (short, just numbers, easy to remember, structured, etc.)

SSNs are account numbers, and only account numbers, for your social security benefits, not an all-purpose resident identity number. they've only been co-opted to be such identifiers because everyone wants to piggyback on, and not additionally pay for, the extra measures the SSA has taken to uniquely identify workers when granting the numbers so we can't easily steal each others' retirement benefits.

tl;dr: SSNs are (financial) account numbers, not people identifiers, and should be treated like bank account numbers (for example).