Thereis examples of AI Art where signature of original artists popped up in the image.Rehashing is precisly what some of those nets do. It learned that for the thing the operator wants, that signature is important. Or those fake pictures of Trump with missing or extra hands. The net was trained with photos, obviously, and on photos hands are often not visible or you see extra hands from different persons.
Those nets that are trained with real stuff are not learning how to do the skill, but to imitate the result by rehashing. With frightenly accurate or creepy results in some cases.
And with copyrighet material that poses legal risks that are not decided yet. To put it blatantly oversimplistic, you can view a trained ai as a filter, like those popular for selfies. And instead of one image you add effects to, you use hundreds images and add a little random and an objective for the result. Like, picture-bot, give me one with that Trump person sitting and eating a burger.
But you still use stuff that you might not have the rights to use or not use in that way. Real persons can do that in some scenarios. But that does not mean that tools (or their operators or the service provider that hosts the tool) are allowed to do that in all scenarios.