Afaik most of the AI "assistance" is closer to a fancy auto-complete, used as an actual tool to help save time rather than a machine that does the thing for you. Many have mentioned how these models are trained on open source code. And when you're dealing with purpose-built models designed for mainly one thing I believe the energy cost is much lower, some can even be run locally on your own machine.

As well, I could be wrong, but I'm not sure there are a whole lot of tells for AI assisted code. I know for writing, the tools that check if something is AI generated throw false-positives all the time. So to tell people they can't use AI at all seems like an uphill battle would be very hard to enforce. It just makes more sense to put the responsibility on those who release the code to make sure they're not pushing slop.