In fairness, I don't think Meta would have (had) any trouble paying the fair price of every book they downloaded (the price of exactly one copy) if that had been possible to do at scale.
Paying the price of one copy does not imply that you can use it for training, right ?
My instinct/gut says that an AI model is a derivative work from the training data (in that it quite literally takes training data to produce a new creative output, with the "human addition" being the selection of training data to use), but there's not really clear judgements on it either way for the time being, which leaves room to argue.
The actual methodology used ("isn't an LLM like a computer reading a book for yourself?") is an irrelevant distraction in this regard. Computers aren't people and don't get that sort of protection; they're ultimately tools programmed to do things by humans and as a rule we hold humans responsible when those tools do something bad/wrong. "Computer says no" works on the small scale, but in cases like this, it's not really an adequate defense.