As far as I understand, BankID actually abstracts away those numbers. FB have to use an API, and more or less receive a true or false on their query.

They recently opened up for using BankID to prove your age at bars and such, and I think they only get to know if person is old enough or not. Not even a number, just old enough.

Addiction is an example, the thing that makes you feel good in the short term, is the same thing that mess you up in the long term, and the only thing that makes the thing bearable is more of the thing, completing a fucking horrible cycle.