It's a herd thing. We have difficulty choosing to do anything drastically differently from the rest of society, and raising children involves another being who doesn't necessarily have freedom to consent so society gets even more involved if what you are doing is deviant. But the drift of society has caused the norm to be something that decades ago would have been considered highly deviant. If you were a hovering parent like is common today in the 60s or 70s, you'd be an absolute freak and considered abusive. But today the opposite is true.
I'm glad you mentioned that the kids are sometimes the ones who make the choice themselves. I guess we're putting so much fear around them that it's making them decide the wisest course of action is to do what is normal and practiced by all their peers, be in constant sight of their parents. Really a shame.