We can get the best of both worlds: privacy and age checks. The governments just need to implement ZKP passports/IDs and give them to everyone.
As things stand, the only sensible way to keep kids off of social media, porn, etc is client side filtering and controls. It would be straightforward to write legislation that requires device manufacturers to make parental control settings available in the setup stage, and require websites over a certain number of users to publish content labels asserting suitability for people under 18, 13, etc. Every other approach is a backdoor mandate for identity verification, dishonestly cloaked as "age verification" for "protecting the children". And I say this as a parent who will be staring down the digital heroin industry in a few short years.