As an undergrad I was heavily involved in the student-led academic integrity organization. This story reads so true to my experiences (from the last millenium, mind you - there was no whatsapp, etc.). My largest cases came from the computer sciences departments. Students thought nothing of copying programs and submitting them as their own.
It turned out, of course, that structural similarities are so obvious. My worst case had 23 students accused of submitting the same program for a lower-level course. I held an event where all (or most) of them attended. Somehow they tried to explain how their use of not-just-similar-but-exactly-the-same variable names, structure and comments in a C or C++ (it's been a while) program. I mean, exactly the same. One spent an hour berating me on the phone (well before I figured out that I could just politely end the conversation and hang up) explaining that it was his work. It was not.
I was disappointed over and over seeing how blatantly and cavalierly my fellow students would break the rules. It was unpleasant for everyone involved, despite a reasonably lenient punishment process - students, faculty and us alike. I didn't like lording over my fellow students, but felt it was important to hold a line of sorts. I wish very much that there was no need for this function but time and again students turned in work that was not theirs. I strongly suspected at the time that most professors only turned in the most blatant open-and-shut cases. It was particularly sad considering how very much money each class cost.
It turned out, of course, that structural similarities are so obvious. My worst case had 23 students accused of submitting the same program for a lower-level course. I held an event where all (or most) of them attended. Somehow they tried to explain how their use of not-just-similar-but-exactly-the-same variable names, structure and comments in a C or C++ (it's been a while) program. I mean, exactly the same. One spent an hour berating me on the phone (well before I figured out that I could just politely end the conversation and hang up) explaining that it was his work. It was not.
I was disappointed over and over seeing how blatantly and cavalierly my fellow students would break the rules. It was unpleasant for everyone involved, despite a reasonably lenient punishment process - students, faculty and us alike. I didn't like lording over my fellow students, but felt it was important to hold a line of sorts. I wish very much that there was no need for this function but time and again students turned in work that was not theirs. I strongly suspected at the time that most professors only turned in the most blatant open-and-shut cases. It was particularly sad considering how very much money each class cost.