I had students that copied one-another's work; in fact I had few students that didn't copy. It made it impossible to mark their projects correctly, so I asked my more-experienced colleagues.
The best advice I got was to explain the difference between collaboration (strongly encouraged) and plagiarism (re-take the course if you're lucky). Forbidding collaboration is a disastrous policy, so an instructor shouldn't have a problem with giving the same mark to each member of a group of collaborators. You just have to test that each individual can explain what they've submitted.
My school auto-graded everything (file drop your code to a server by midnight & get a score back). I don't recall a single instance of TA/professor written or verbal feedback on code.
Yuh. I guess that's "modern times". I taught in the late eighties, and auto-grading wasn't a thing.
FWIW, I was a "temporary visiting lecturer", i.e. contract fill-in help. I had to write the syllabus (literally), the course plan, and the hand-outs. I also had to write all the tests and the exams; and I had to mark the exams, and then sit on the exam board through the summer holidays. The pretty girls would flutter their eyelashes at me, and ask for leniency. I suspect they took their cue from my louche colleague, who was evidently happy to take sexual advantage of his students in exchange for better marks.
[Edit] I liked this colleague; but I would not have introduced him to my wife or my daughter.
This was in the 1980's. We're talking 5 1/4" floppies, no internet, 64MB RAM. I had to review my students' work as dead-tree submissions or completed circuits or whatever.
(I certainly wasn't going to take digital submissions from them; that would mean floppy disks, and I regarded any disk that had been touched by any student as if it were infected with plague, because it almost certainly was. All the school systems were always infected).
The best advice I got was to explain the difference between collaboration (strongly encouraged) and plagiarism (re-take the course if you're lucky). Forbidding collaboration is a disastrous policy, so an instructor shouldn't have a problem with giving the same mark to each member of a group of collaborators. You just have to test that each individual can explain what they've submitted.