This is a valid point but Amazon also sells a lot of books based on pseudo-science and debunked claims. It's pretty clear they are not an ethical company so they absolutely will do nothing to stop AI generated books.
For anyone that thinks AI books are not a problem, I recommend this article and the Behind the Bastards two-parter that goes along with it: https://shatterzone.substack.com/p/ai-is-coming-for-your-children