My first year of university I attended a school in Alabama. Most of my classes were pre-engineering but also general classes like English Composition and Music Appreciation. There were never any class interruptions or behavioral issues.
Then I moved to California and took a class at Moorpark College. I was floored by the number of students acting like it was a high school class, sitting at the back, talking the entire lecture, laughing, and generally not giving a shit. The professor didn't say anything and just tried to ignore it.
The next year I transferred to Cal State Northridge. The professors there didn't put up with that shit but it still went on. The difference was that the troublemakers got kicked out of the lecture. This didn't happen in every class but happened frequently enough for me to start developing hatred for these idiots. What the fuck were they even doing there if they didn't want to learn something?
It got better once I got into more of my higher level major classes but it still amazes me how many students there were in university classes who behaved like high school shitheads.
In ended up in Tennessee for grad school and just like my freshman year in Alabama, no one causes trouble during class. But the classes were 95% Chinese and Indian so even if they were shitheads, they probably knew getting kicked out could mean getting sent back home and fucking up their opportunity to stay in the US.