Except the majority of kids have smart phones now and the rates of mental health issues have skyrocketed.

"What kind of kid can resist the lure of a phone until she 18? "

They don't need to resist it on their own. You just need decent parents that don't promote it at a young age. Yeah the kid may get out on their own and touch a few smart phones but if you don't addict them to it at a young age they'll be less interested in using it as a constant coping mechanism. Additionally, someone has to actually buy these devices for them. If they have to spend their own money on this stuff it's less likely they'll have them.