A long time ago at a university not far away, I and a few classmates all turned in the same report for a group project. The teacher absolutely and rightly thought we were cheating, after which we explained that we interpreted the instructions to mean that a group project would have a group paper. He seemed to accept this and gave us like an extra week to compile our own papers, but he must have smoked an extra bowl that night. I know I would have if I was a professor in that situation!
I've taught university classes, and failed students on the class for cheating. But it's true that I haven't seen anyone kicked out of a program or a university for cheating.
Anecdote: Foreign student where I went to school flat out cheated on the final. When caught, he copped to it. A humanities prof then went to bat for him, saying that it was okay to cheat where he came from. They didn't expel him.
This is a general problem with any punitive measure. There will be some false positives (unfair punishments).
I actually do know someone who was not able to get a CS degree because of 'cheating'. His story was that he was working in a group, got verbal clearance from his professor that this kind of collaboration was acceptable, and when that auto-cheating-analysis tool flagged each group members work, the professor claimed not to have said that and was uninterested in fixing the problem.
So, this absolutely does happen. OTOH, I've never personally had any experience with 'borderline' cases. There were enough cut-and-dried cases to keep me busy.