You are most likely referring to the EU covid certificate. It functioned as a proof of vaccination or recent negative test, and yeah, that was required for travel at one point. And even then the verification end was `(code: string) -> valid: boolean` function, no personal data was accessible at validation point. It used the digital ID as SSO for accessing your records, so you could save / print the verification code, usually in form of a qr code. I know all this, because I'm friends with people that worked on the Latvian part of the system, and we spent long chat sessions discussing how to best do it in the least privacy-intrusive way.

If you were from outside EU, I fully believe the experience was subpar. 99% or more of verifications went through the EU system, and if you showed up with different kind of documentation, the people tasked with verification "at the edge" might not even know if it was valid form of proof.

Overall, I struggle with being outraged by the concept of digital ID. It's just a digital form of "show me your passport please". We have had physical national ID (mandatory from certain age!) for as long as I can remember myself. The state knows I exist. If a madman gets put in charge, lack of unified digital ID is not going to prevent airport style passport gates being erected around the booze stand.