Not disagreeing, but I think it's better to see this from a slightly different perspective:

> But because it was a nationally unique number for every individual, it got used as a primary key for all sorts of other things, and it ended up becoming very sensitive.

What makes it so sensitive is not the fact that it identifies a person and it's used everywhere, it's the fact that it's being used the wrong way. Absolutely no authentication should be done solely on the basis of the SSN. You can still have it be the primary key, but that shouldn't grant authentication by itself.

The Brazilian CPF is the same in identifying a person and being used everywhere, but it's not used a the sole mechanism of authentication as often as the SSN is used, although when it is then it ends up suffering from the same problem.

The only way to really solve this is for governments to enforce that solely knowing these types of IDs can't lead to any authentication, that's unacceptable and should be treated the same way knowing the name of a person is (which funnily enough some governments also treat it wrongly in similar ways, but you get the point).