Gotcha. That was my misunderstanding then. I've seen people talk about something similar: a government issued "id" (potentially tied to your driver's license or whatever) that digitally identifies that the holder is of a certain age, but nothing more. That's what I thought you were proposing here as well.

I don't think there's anything wrong with your idea, but it also seems unnecessary, and makes it easier for businesses to track you - not harder. If the purpose isn't to obfuscate information, they can just look at a driver's license and see their birth date and that the picture matches the person using it. It also doesn't really have anything to do with the subject of the post (online age verification).