[wibbily]

Seems like it could work in the other direction... mandate that adult sites etc. include a standard, relevant flag in the response, so that parental control software can detect it if it's installed. Sites don't have to know anything about their users, parents can reliably filter out naughty sites.

To op's point, age verification is really a surveillance measure, so this won't happen.

[reactordev]

That would be a better approach. Let the sites that require it, negotiate with the browser to get it. Oh wait, isn’t that what we are asking them to do and they won’t? They’d rather shut off access entirely.

No the best approach is having parental controls on device and require whitelisting and established accounts that the parents setup. Anything else is making the web a more restrictive place for all.