Code doesn't always speak for itself. I've had to do some weird things that make no sense on its own. I leave comments but they are not always easy to understand. Most of this is when I'm sharing data across threads - there is good reason for each lock/atomic and each missing lock. (I avoid writing such code, but sometimes there is no choice). If AI is writing such code I don't trust them to figure out those details, while I have some (only a minority but some) coworkers I trust to figure this out.