I've experienced both. Some schools are really good. The private K-12 religious school I went to treated kids like people and still set boundaries. The local public high school did the same. The public grade school was a horror show. College was particularly interesting. Most of the administration did not care about students as people. Everyone else did.
You need to talk to work with some high schoolers then. There is a large chunk of that population that the school is in their orbit. They casually treat people like objects. They don't just tune out, but actively disrupt anything going on, ruining the days of teachers, staff and students -- for sport.
Where? I don't see any of it, let alone dripping amounts.
But yes, I'd love to send my kids to a school where the principal was strongly anti-cell-phone.
[EDIT] My main concern over the next few years is social pressure of the "you have no phone, so your family must be poor" sort. We've had a 2nd grader teased for being poor because she "only has one backpack". LOL. I have some uncharitable thoughts about those families.