Hands are tough. I've been studying and painting them for over 20 years and they remain a challenge. It's kind of funny that that's the thing AI stumbles over. I think it's a combination of training data, hallucinations, and our own sensitivity to hand positions as a stand-in for body language - very easy to wind up in the uncanny valley with hands. I'm sure they'll crack it at some point though.
I don't know this for a fact, but I wouldn't be surprised if most AI image generators excluded stuff from explicit websites so they weren't constantly churning out weird porn in response to even the most anodyne request.