The thing that makes this plausible is that the California and Colorado bills are specifically written to either allow or outright require self-attestation. Children will just lie about their ages because if they don't, the computer is basically useless. So it would give Meta the ability to dodge lawsuits, but still actually have kids on their dangerous platforms, with the argument of "well, the law makes us trust this unreliable indicator".

> Children will just lie

Not if the parents are setting it up beforehand (like with small children) then their iaccount or Google account will be under parental controls from that point on.

It seems reasonable that if a parent enables their child to visit sites after that, then that's just their prerogative (like giving your kid beer)