There are plenty of spaces where alcohol use or being drunk are not allowed, does that mean that alcohol usage in these spaces is running rampant? No. Because there's a difference between a complete societal ban and restrictions in certain areas.

You could easily ban phone usage during classes and allow kids to use their phones during breaks, with the punishment for using them during class being confiscation until the end of the school day. You can teach digital literacy and responsible usage of technology and/or the internet without kids having their phones in their hands when you teach it.

Apps are made to be addictive, it's understandable that kids could have issues concentrating on things that seem less interesting when an entertaining distraction is right at their fingertips.