Everything plays a role. Pop music certainly does, but phones are worse. That was one of the things that disappointed me while I was trying to shift to teaching in the US - teachers are mostly not allowed to take away phones, and the exceptions are only after state-level legislature that prescribes when and how they can take away phones. Teachers in the US really have their hands tied, and any slight deviation (in one direction) equals prompt dismissal.
The 1950's, I think, was different in that there was a kind of momentum from previous generations still affecting them. Our society was just beginning to be litigious and heavy with policy. A lot of schools still taught marksmanship, with real guns. People in general were tougher and more responsible. But if you go back to before ww2, classes were mixed ages and several grades were together in one classroom. Modern school structure is modeled after British schooling, mostly invented at Cambridge, and it was pushed in the US by Roosevelt and all his socialist bullshit. IMO, Roosevelt murdered America, and only a few people are able to see it now because the detrimental affects of policy unfold over generations.