Good overview of the issues. I'm sure there are a few nits to pick with that.

But something that is overlooked is that the world is bigger than the US and it's an absolute zoo out there in terms of copyright laws in different countries. Anything you think you might understand about this topic goes out of the window if you have international customers or provide software services outside the US. Or are not actually based there to begin with. And there are treaties between countries to consider as well.

Courts tend to try to be consistent with previous rulings, interpretations, etc. When it comes to copyright, there are a few centuries of such rulings. The commonly held opinions among developers that aren't lawyers are that AI is somehow different. And of course since the law hasn't actually changed, the simple legal question then becomes "How?". And the answer to that seems to involve a lot of different notions.

For example, "AIs are not people, and therefore any content produced by them isn't covered by copyright to begin with" is one of the notions brought up in the article. A lawyer might have some legal nits to pick with that one but it seems to broadly be the common interpretation. So AI's don't violate copyright by doing what they do. In the same way you can't charge a Xerox machine with copyright infringements. Or Xerox. But you could go after a person using one.

And another notion is that any content distributed by a human can be infringing on somebody else's copyright and that party can try to argue their case in a court and ask for compensation. Note that that sentence doesn't involve the word AI in any way. How the infringing party creates/copies the content is actually irrelevant. Either it infringes or it doesn't. You could be using AI, a Tibetan Monk copying things by hand, trained monkeys hitting the keyboard randomly, a photo copier, or whatever. It does not really matter from a legal point of view. All that matters is that you somehow obtained a copy of an apparently copyrighted work. AI is just yet another way to create copies and not in any way special here.

There are of course lots of legal fine points to make to how models are trained, how training data is handled, etc. But if you break each of those down it boils down to "this large blob of random numbers doesn't really resemble the shape or form of some copyrighted thing" and "Anthropic used dodgy means to get their hands on copies of copyrighted work". I actually received a letter inviting me to claim some money back from them recently, like many other copyright holders.