In part I see this as the legislature stepping up to be the bad guy, and taking pressure off schools. School administrators know phones are a problem, but a minority of students and parents are very vocal and make it hard to put bans in place.
Pretty much every school allows teachers to ban phones in their class, so we have the fully devolved approach already, but it just puts the burden on teachers, it's not real autonomy.
“vocal minority is very loud, everyone else disagrees but are too busy to come yell at electeds, so we can’t fix this obvious problem. Done. Problem festers”
I'm in Minnesota, I'm just assuming California has the same problems. The issue is pretty nationalized.
Some of it is students having a genuinely disturbing attachment to phones specifically, like a sense of anxiety when the phone is gone. There's also parents who get really freaked out about school shootings and are anxious that they won't be able to be in contact with their children. I guess it's kind of similar. Anxiety does not bring out the best in people. (And I note the page specifically refers to this concern)
As a parent it's also handy to be able to communicate with my child about logistics during the day. Parents can be kind of whiney about that sort of thing. Whiney parents should be the basis of policy, but obviously it happens...
Pretty much every school allows teachers to ban phones in their class, so we have the fully devolved approach already, but it just puts the burden on teachers, it's not real autonomy.