This is unironically a good method. It ensures privacy by breaking any traceability between a person getting verified and the verification being provided to a site. The verifier sees your ID and declares that yes, you are of legal age. They give you a token that says “the bearer of this token was verified”. The token is provided to a site. The site can see that you were verified, but learns nothing more about you.

It’s literally how blinded digital signatures would work, which should be the only way that this kind of thing gets done, if it really has to get done at all. Not uploading your photo ID directly to a site, or to a verifier who partners directly with the site. Certainly not completely unreliable face recognition bullshit. Or to make the analogy slightly more accurate, it would be like if you signed your username on an empty bottle, put the bottle in an opaque brown paper bag, took the bottle to the bottle-o, and they filled up the bottle with alcohol without removing it from the bag (so they can’t read the username), after verifying your age. Obviously filling up empty containers isn’t a thing bottle-os do, but hypothetically if it were, this would be the analogy.