> Isn't this a basic requirement of any ID system?

And now you understand my core opposition to government run ID system.

Think of it like SSH keys: you want them to allow access, and therefore one-way verification. You don't want a bijective system that would allow you to be uniquely identified. So you can have 1 key per system you access.

Most uses of ID are compatible with that usecase: one ID to allow you to pay taxes, one ID to allow you to travel, one ID to prove you have a license to drive, etc.

There's absolutely no need to merge them - except for the convenience of tracking you and adding new usecases easily, without the government shouldering the burden of rolling a new ID AND having people use it.

If there was no cost having an ID that could serve for the sort of purposes you mention, I might agree with you.

But I have no desire to see a society in which zero-cost (or effectively zero-cost) ID systems are the legal requirement for those purposes. As a result, issuing and maintaining the records associated with physical world forms of ID have real costs associated with them, and I would question the benefits to society (even with "privacy" in mind) of replicating that per-potential-ID-category.

[ EDIT : Also, I would think that the way browser fingerprinting works would dissuade you from believing that one-ID-for-X and one-ID-for-Y is going to stop you from being uniquely identified. ]

If you had an ID system that allowed you to get multiple unconnected IDs, what would prevent someone from getting 10 million of them and casting 10 million votes in an election? Or even just having 2 or 3 and claiming stimulus checks or welfare or disability or whatever?

Doesn't the government have to be able to uniquely identify you to even have a chance at providing services equally to everyone?

1. it remains to be seen, 2. should it happen, it would be illegal and expose the perpetrators to jail time

Overall, I'm not so sure the status-quo is worth the tradeoff, especially when accumulated at the population level (10 000 people commiting stimulus check fraud is what, 0.01% of the population?)