> Surely the problem of verifying a property of someone (the Boolean of “is over X age”) without sharing further details, is a surmountable problem given all the cryptographic technologies at our disposal.

Only if preserving privacy is the goal and I'm sure we both know it isn't.

I guess it will become self-fulfilling if everyone denies that there are privacy friendly options. Legislatures globally are starting to take this seriously so chances are it's happening one way or another.