It's similar in France. In addition, each government service uses a different ID number and is forbidden from sharing information or using another service's ID

It's similar in France. In addition, each government service uses a different ID number and is forbidden from sharing information or using another service's ID number. So you have a fiscal number for taxes, a social security number for health things, an identity card number that only has meaning with the card itself. Your private (non-healthcare) insurance, your bank, and other private institutions can issue you their own number as well (or another kind of id key) but can not share them between themselves and cannot ask you to give them numbers of unrelated services. Citizens are responsible for forwarding themselves most information between separate services when needed. In practice it makes it sometimes tedious to auth at any of these services (you have to find your number in whatever mail you received or card you got issued) but it really makes it more difficult to impersonate another citizen, as you would at most gain access to one service, and it wouldn't help you access any other.