This is all to say: the question about copyright remains exactly the same regardless of license.
I do not disagree with what you said, only that in reality, this is not the only way business conflicts are decided.
This never happens, you will first learn from a book or tutorials.
But your idea is sound, have Microsoft buy books from the authors and train the LLM on those books then have the LLM solve new problems. If is an AI and not a text interpolating tool then it should be able to learn like humans from a few books.
I have learned to code almost entirely from reading code. I hate tutorials and books.
I occasionally skim docs but mainly for the code examples.
So "never happens" is a curious take.
The word "remixing" here is useful because it will fit any conclusion the reader prefers.
Arguably even in your reductive example, the result would be non-infringing. Or not. Which conclusion you reach is exactly the topic under debate. Isn't this textbook question begging?
Imagine I get the Windows source code and rename the variables by adding a "314" after each varaible, after each function name and rebuild Windows, in your definition this is remixing and fair ?
Where you like it or not this is an undecided area both legally and morally. Pretending it's clear cut is either disingenuous or delusional.
My simple example is to show that is not as simple as "the AI earned from N devs GPL code and now it can spit new original code without ZERO concerns", we know how this stuff works and that it can spit out the exact training input in some cases.
So IMO a judge should ask the question "from how many people you need to steal, mix the input to be sure the output is actually original".
And about the thing "if I read someone code it is not stealing" , hyumans are different and even for humans it is not allowed to read the code of your competitor and then write new code using that knowledge.
What if you train it only on my huge repo of GPL code? You are just remixing my code.
Now you maybe think "let me train on 2 different devs GPL code", the remixed code will probably be 50-50 and you can get away with it ?
If the 2 number is too small then tell me what the number N should be ? From how many people you need to "steal" code , mix it and the output is "original" ?
Edit: my opinion is that AI should be fair, if you train it on open source then model should also be open source and output should also be open source.