Apparently parents love it as it keeps the kids quiet and relieves them of the stress of parenting.
Also a tracker and a way to contact them at all times. I believe parents who let children take phones to school would feel a bit nervous if their kid would forget it at home one day.
I get why people do this but if I was being tracked when I was a kid, especially after age 16, I would be furious. I would have done something like hide it in a hole beside the movie theatre so I could go smoke some weed and have sex with my girlfriend.
As a parent, it is convenient to have a handy device to zombify my hellspawn for an hour while I need to get some actual important adult shit done, but I also strictly limit mobile device use because my kids will not be iPad kids for as long as I have any say in the matter