The LLMs for text are also based on "theft". They're just much better at hiding it because they have a multitude more source material. Still, it does sometimes happen that they quote a source article verbatim.

But yeah basically they're just really good copy/paste engines that work with statistical analysis to determine the most likely answer based on what's written in basically the whole internet :P It's a bit hard to explain sometimes to people who think that the AI really "thinks". I always say: If that were the case, why is the response to a really complicated question just as fast as a simple one? The wait is just based on the length of the output.

In terms of the "theft" I think it's similar ethically to google cache though.