It is literally illegal to slap a few lines of glue code and say “there’s your age verification, look how cheap it is.” The public would be happy about saving money right up until there’s a massive privacy breach and all the ways you cut corners are exposed.
I don’t know if leaving the standards unspecified is the right thing to do (it’s probably not), but don’t pretend like a government verified solution could ever be cheap when dealing with citizens’ identities.