It appears that it's hard to detect AI generated content. E.g. true detection rates are only around 25% and there are also techniques to further mask output [1].
You only need enough to flag suspect content, and then the teacher calls the student in for a quick oral exam - the fakers will flounder, the reals will pass.
Even if you understand the material well, doing assigned tasks takes a lot of time. Especially if it's free form text. And "I want to do something more interesting right now" is at least as powerful a motivator to cheat assignments as "I don't know how to do this".
Aye, if I mostly know a subject why bother to take the time to write 10 pages when I can outsource that to a bot, and if they question me I can do a 20 min oral interview and save myself the trouble?
[1] https://www.nbcnews.com/tech/innovation/chatgpt-can-help-foo...