Creative Commons has a new set of AI licenses, CC Signals: "This is not about creating new property rights; it is more like defining manners for machines."
Hmmm, some of these machines already ignore robot.txt files, so I'm not sure how well this will work. But CC *did* revolutionize copyright licences in early Web 2.0, so I'd certainly like to see them help out in the AI era.
https://creativecommons.org/ai-and-the-commons/cc-signals/implementation/