School is ruining kids lives
I'm half-joking.
But one of the main purposes of school is to keep kids there all day so that when they get older they're trained to be at work all day.
Don't fool yourself that kids are absorbing useful information 8 hours a day and the phone is detracting from it.
Human beings have a limit to how many hours they can study and learn. And it aint 7 am to 4 pm and then homework. It's just mostly drudgery to prepare them for the drudgery of work later on.
And thats one reason kids behave badly. Because they dont want to be trapped there all day.
A more humane school system would be 3-4 hours a day max of studying, and the rest play, art, dance, sports, video games ... no homework.