Is there a way to prove your age without being identified/logging in? Surely some kind of OpenID style protocol can be invented for this with zero knowledge of personal information ending up with pornhub or which sites were being given age verification?
Why not turn this around? 1. Introduce a X-PEGI HTTP header that sites can use to change the content. This would also be useful for other contexts such as cybercafes and whatnot. 2. Mandate that porn website abide by these headers. 3. Have responsible parents, lock their children's computers and add the appropriate header. The adults then have access to the adult internet with no extra restrictions.
There's yer problem right there.