I couldn’t care less about children or about what is ultimately a parenting issue (keep your fucking kids off the internet). A problem that affects a subset of the population is not something that should be solved by subjecting the entire population to inconvenience. Just make it illegal to use the internet for under 18s or under 16s or whatever and let it be assumed that all users are of the appropriate age.

If I a child is on the internet without adult supervision, that’s a parenting problem, not an issue for the state or other people to solve.