I'm pretty sure that has nothing to do with it, because in Japan kids generally have far less time to be kids due to the rigorous school system and testing focus. That in turn leads to Japan's increased rate of suicide among the youth.

It's not illegal: https://www.fastcompany.com/3055107/federal-law-now-says-kid.... But it is frowned-upon by the society.

It's frowned upon, and a federal law isn't going to stop local cops from hassling parents. Remember, cops don't actually have to follow or enforce the laws, they can basically do what they want, and if you don't like it, your only recourse is to sue.

Right, but your original claim was that it's illegal and that's what I was responding to.