Agree with the middle part - At the moment, the policy implemented by corporate is "Don't ask; don't tell". If someone says they used GPT or other AI for their answer, it's disallowed. If they try to hide the fact, there's not much the community can do to get it removed.
And while I'm not a moderator, as just a user I've flagged over 1,200 answers on Stack Overflow (and several of the smaller communities like Ask Ubuntu) that were subsequently removed. Automatic detection was never the sole criteria that was used to determine if it was AI - It's entirely possible to spot GPT content using multiple methods. I don't publicly talk about most of these, since we do have a group of users (sometimes spammers) who attempt to hide their use and make it more difficult to detect. See some of my additional notes on the topic on https://meta.stackexchange.com/a/389674/902710
And while I'm not a moderator, as just a user I've flagged over 1,200 answers on Stack Overflow (and several of the smaller communities like Ask Ubuntu) that were subsequently removed. Automatic detection was never the sole criteria that was used to determine if it was AI - It's entirely possible to spot GPT content using multiple methods. I don't publicly talk about most of these, since we do have a group of users (sometimes spammers) who attempt to hide their use and make it more difficult to detect. See some of my additional notes on the topic on https://meta.stackexchange.com/a/389674/902710