At the school I'm at kids aren't allowed phones in class. Most don't. Kids still have in pockets but they get taken off them if they're being used.
Honestly I work with a lot of mature kids. Yes they still need life experience but I don't think we give them credit enough for being intelligent - sure, their brains need to develop more but jeez there's some bright sparks out there. Kids are incredible. But I wouldn't have been a teacher if I didn't think so