I think my extraversion is probably a factor. Personality differences almost certainly mean that different environments will better suit different people!
Fwiw, I went to a state school as well (in the US). But by the time I was at the university, I already had a two-year degree, and all of my general education requirements were already fulfilled. So my first few years in college had the benefits of very small class sizes and a genuinely diverse student body (i.e., students of all ages from high school students doing dual-enrollment to retirees pursuing 'continuing education', students who were parents, students who were military veterans, students who had had already had careers in trades, students who were working full time, etc.), plus they were (mostly! some of the science and math classes were genuinely demanding, being taught either by passionate teachers or for supplemental income by university instructors who didn't want to bore themselves create extra work by dumbing down their curricula) easy enough that I had a ton of free time.
And then the last few years of it were comprised entirely of upper-division electives, except for a couple of major-specific requirements that the university refused to transfer from the community college. It was still a lot of classes, since I ended up doing a double degree (and part of an accelerated masters program that I ditched come graduation time), but basically all of those classes were (a) in my specialties of interest and (b) my choice. Those class sizes were mostly pretty small too, though some of my computer science classes were still huge (100+ students).
I've myself had work habits that were/are largely mysterious to me. But at any rate, by the time I got (back) to the university, my classes were all advanced enough that the vast majority of students in them were committed to their subjects (or else they were experienced enough to know they should drop the uninteresting class in the first week and take something better for them instead).