They're probably training them to refuse, but fundamentally the models are obviously too small to usually memorise content, and can only do it when there's many copies in the training set. Quotation is a waste of parameters better used for generalisation.

The other thing is that approximately all of the training set is copyrighted, because that's the default even for e.g. comments on forums like this comment you're reading now.

The other other thing is that at least two of the big model makers went and pirated book archives on top of crawling the web.