Identity numbers being abused is a consequence of them being misused. And as far as I can tell, this happens more often with american SSNs than anywhere with actual national identity numbers.
All that these numbers do is uniquely identify people. They aren't private. To actually prove your identity, you present your ID, passport, or a digital signature tied to that identity number.
You’re talking about different things. Sweden has personal identity numbers and they’re public information. It protects you from being mixed up with someone with the same name. Not from identity theft though.