If you look at a hundred paintings of faces and then make your own painting of a face, you’re not expected to pay all the artists that you used to get an understanding of what a face looks like.
Even if AI companies were to pay the artists and had billions of dollars to do it, each individual artist would receive a tiny amount, because these datasets are so large.
Much more realistically, they would just retrain their models using data they can use for free.
Btw, I don’t think this is a fair use question, it’s really a question of whether the generated images are derivatives of the training data.