Not Swedish, but the relevant one in the parent comment is probably mandatory residency registrations, and I'm surprised the data is so publicly accessible there. There are usually attempts at creating firewalls in many countries so the data that one agency collects isn't directly linked to that of other agencies, preventing broad files on individuals.
It's similar in the sense that it's a unique number assigned to each person, but the fact that it's publicly available means that it cannot be used as authentication.
We have a similar issue with Finnish Personal Identity Codes, which are legally public, but there are restrictions related to their processing. Which leads to the common misunderstanding that they're secret, so they're used for authentication. It's a mess.