In my degree (Comp Eng) we overlapped with the Comp Sci program a fair amount. Comp Sci was part of the college of mathematics and Comp Eng was part of the college of engineering, which were on opposite sides of campus and organizationally were very separate. The cultures could not have been any more different. The engineering labs were loud, full of collaboration and discussion. The professors would sometimes find o…
In freshman engineering courses [*], students would gather and do the assignments. They would divide and conquer questions, sharing answers. This was definitely cheating. (I didn't participate. But I didn't seriously consider reporting it either; I wanted to have friends...) The assignments were repetitive and stupid, so this was a rational if dishonest coping strategy. TAs certainly knew this happened. I had a bad habit of skipping dumb assignments. One TA actually emailed me something along the lines of "why don't you just cheat like everyone else".
In physics classes, students would gather and do the assignments. They would each do all the work. When someone got stuck, others would suggest techniques, help them where they were stuck, etc. Collaborative and honest. The assignments had far fewer problems, each unique and involved, done from first principles. Homework was graded on showing (extensive) work as well as the answers. If folks had skipped/copied problems, they would have missed out on great learning opportunities and likely flunked the exams even if they weren't caught.
In computer science classes, I don't recall students gathering to do the assignments. Maybe I just wasn't part of the group. (Many of my friends were in engineering, and most of my academic time was spent in the physics building.) Maybe they just didn't work together, similar to what you observed. What I do know is that a lot of students had very little understanding, and I was surprised they got degrees.
Of course, I prefer the physics approach. It's probably not a discipline-wide thing though as much as that my school had a great physics department and a lousy CS department. More similarities than I expected in your story, though, despite presumably different schools and times.
[*] I dropped my electrical/computer engineering major after freshman year. I graduated with a comp sci major + physics minor. Maybe later engineering courses were different.