I was a TA years ago, before there were LLMs one could use to cheat effectively. The professor and I still detected a lot of cheating. The problem was what to do once you've caught it? If you can't prove that it's cheating -- you can't cite the sources copied from -- is it worth the fight? The professor's solution was just to knock down their grades.
At that time just downgrading them was justifiable, because though they had copied in someone else's text, they often weren't competent to identify the text that was best to copy, and they had to write some of the text themselves to make it appear a coherent whole and they weren't competent to do that. If they had used LLMs we would have been stuck. We would be sure they had cheated but their essay would still be better than that of many/most of their honest peers who had tried to demonstrate relevant skill and knowledge.
I think there is no solution except to stop assigning essays. Writing long form text will be a boutique skill like flint knapping, harvesting wild tubers, and casting bronze swords. (Who knows, the way things are going these skills might be relevant again all too soon.)
At that time just downgrading them was justifiable, because though they had copied in someone else's text, they often weren't competent to identify the text that was best to copy, and they had to write some of the text themselves to make it appear a coherent whole and they weren't competent to do that. If they had used LLMs we would have been stuck. We would be sure they had cheated but their essay would still be better than that of many/most of their honest peers who had tried to demonstrate relevant skill and knowledge.
I think there is no solution except to stop assigning essays. Writing long form text will be a boutique skill like flint knapping, harvesting wild tubers, and casting bronze swords. (Who knows, the way things are going these skills might be relevant again all too soon.)