Quite apart from all the safety stuff, I really don't know how parents can AFFORD to equip their kids with smartphones. I dropped mine down the bog a couple of weeks ago, and a replacement - a bottom-of-the-range Pixel 7 that no self-respecting teenager would be seen DEAD with - was the thick end of £400.
In my experience, children have a pretty poor understanding of the value of things, and loads of phones must get lost, stolen, dropped (not necessarily down the bog), and need replacing or repairing.
If you've got 2 or 3 kids, that's an astronomical expense, before you get onto data plans and so on.