This seems more like a technical problem that we could actually solve well if we wanted to and had competent people advising the governments. You go to DMV and they generate a keypair and an entry in a DB. App looks up your age with your public key + signed private key authorization from you. Apps can ask for specific checks like is_over_21, is_citizen or whatever without any more data. Something like that, details are probably off ;) The whole infrastructure could be open source. Age verification doesn't need to equal identity verification by a 3rd party company that will leak your IDs.