> A true zero knowledge ID check with blind signatures

That is not true and "true zero knowledge ID check" + "age verification" with blind signatures is what's being implemented by the EU ID project.

So someone's id leaks. It happens. In EUDI there are things called "cryptographic accumulators of non-revocation proofs". If your ID leaks it goes into the accumulator. Similar to the certificate revocation lists. During check, you include claims "im over 18" and "my id is not in the accumulator".

This is included in the standard.

This is also (I can only assume) one of the reasons why EUDI wallets require play integrity / attestation / secure element on the device. So your private key won't be easily leaked and no one can steal your ID.