>Creating derivative products you charge for surely can't be considered fair use?

All US courts so far have ruled yes.

Of course it is. If I write a movie review and sell it to a magazine or whatever, it's derived from the movie, and it's fair use, and I don't need to ask the movie owner for permission first, or give them a cut of my sales. Even if I use some reasonable number of screenshots and video clips, as long as the resulting work is "transformative" i.e. actually a new work, a movie review instead of a copy of the movie.

Do you want this to work any other way? I constantly see people in the AI debate working themselves into wildly copyright maximalist positions. I actually don't think that we should give every author veto power over a book review!

IANAL but as an IP creator I have not heard of "derivative products" in the copyright context. There are "derivative works", which are covered by the same copyright as the original. For example, a translation to another language is a derivative work, a novelisation of a movie, a screen adaptation of a book etc. If some author could have proven that any Anthromic model is a derivative work of theirs then they had the copyright on that model and made mad bucks licensing it back to Anthropic.

YouTubers monetize fair use all the time. Is that significantly different?