Parenting.
It's that simple.
My granddaughter is almost 14. She still does not have a cell phone. She does chores after school, and during the summer. She "works" in the Jim Chambers shop with her Mom as well. She will also be with the family during a trip to Friendship, to the beach, and is attending a summer camp. She has a list of books to read during the summer. All in all,,,, she is doing "things" vs. spending time in front of a TV or on some form of modern social media with a mobile device.
When you get kids involved in activities, WITHOUT their cell phones, they do other things. It's how you structure these other activities that can determine what kind of person they are. Monitor their friends & what they are doing. Because if you just turn them loose,,, they can still get in trouble. Still, we have way too many folks who are so immersed into their little electronic devices, the reality passes them by.