I sympathetic to this perspective, as a parent, but also, there are just a lot of kids out there with bad parents.

My personal philosophy is that parents have a duty to raise their children but that duty is on behalf of the society into which the children will eventually enter. Consequently, a just society may sometimes impose itself on parental freedoms (in the case of neglect, for example) because, in the end, the child's ultimate guardian and responsibility is the society itself, not the parents. The internet is full of material exposure to which, for children, could reasonably be construed as neglect or abuse, and it is insufficient to leave the entirety of the responsibility to the parents, in that case.

I don't know why Americans are so obsessed with freedom as if were the only social good that a society can pursue. There are many things which make life worth living, that contribute to flourishing, and freedom is high on that list, but its not the only thing.

All that said, I don't approve of age checks of the sort being proposed everywhere now. We can do a lot better at mitigating these problems without damaging privacy so much.