What would you do? Get rid of mobile computing altogether by government fiat? Ban providing a smart phone to someone under the age of 18? What about tablets and computers, how would one even enforce that? Would you force kids together to socialize for a period of time which is just as likely to develop trauma as relationships?
The only reasonable solution I've heard to the phone problem is individual parents getting involved and active in monitoring and limiting their children screen time, and unfortunately, involved parenting is not something that can be legislated into existence.