We already have standards:
PICS https://en.wikipedia.org/wiki/Platform_for_Internet_Content_...
POWDER https://en.wikipedia.org/wiki/Protocol_for_Web_Description_R...
ASACP/RTA https://en.wikipedia.org/wiki/Association_of_Sites_Advocatin...
What seem to lack is the will power to use them. Or after seeing in the linked site:
*EU politicians exempt themselves from this surveillance under "professional secrecy" rules. They get privacy. You and your family do not. Demand fairness.
they really want mass surveillance for the plebs even by creating a weak point for enemies. To hell not just with rights but also defence. So any excuse will do.
Well don't I feel like an uninformed dumbass. Talk of standards aside, pornhub apparently includes the following header if you visit it.
rating: RTA-5042-1996-1400-1577-RTA
RTA stands for "restricted to adults". So the large websites, ie the entities that would actually be bound by any proposed legislation, are already proactively facilitating network operators and parents filtering them out. And apparently have been all along. Wild.