that's a gross mischaracterization of the situation.

copyright doesn't mean "i get paid", it means "i get to withhold" (see all the out-of-print books, abandonware, etc).

GPL does not mean "you have to contribute back your changes" at all: "The GPL does not require you to release your modified version, or any part of it. You are free to make modifications and use them privately, without ever releasing them." https://www.gnu.org/licenses/gpl-faq.en.html#GPLRequireSourc...

one is about taking access away (for whatever goal), the other is about taking that option away (for the benefit of users).

GPL is a way to ensure that this particular piece of software stays free forever. One thing that GPL definitely doesn't do is "you have to contribute back your changes", it's fully legal to modify and use GPL-based systems and not contribute any changes back; the only thing that GPL prohibits is enforcing copyright restrictions on others when (if!) I pass the software on to them.

In a legislative regime where all software is free, that goal is achieved without GPL so GPL isn't needed anymore; I get the permission to use, modify and redistribute all software as if I had received it with the GPL.

I don't think that's true at all. We can acknowledge qualitative differences and aims and indeed this "special pleading" is the foundation of all law - we select based on our own conceptions of what is right which laws to make; to say that it is special pleading is to say that laws against those actions which cause harm is special pleading - after all, what's so special about harm? Nevertheless, it is possible to imagine a world in which one restriction (or liberalization) is made but another is not. While this requires a competent legislature and judiciary, there is no reason to think it is impossible; the difficulty in making an analytic distinction is only a small speed bump.

The author already doesn't control all aspects of distribution. It's for example okay to use copyrighted works for satire in many legislations. So lawmakers already agree that there are legitimate uses of copyrighted works that are out of control of the copyright holder. If we wante to we could extend such uses to include filesharing.

You are creating a false dichotomy by using the word stealing in the first place.

If you accidentally take a picture of my shitty origami art project you are not stealing

If you walk into a factory and take the mold for a military sonar device you are stealing.

At what point does changing the first story into the second story does it become stealing?

Either you can pinpoint a minimal set of changes in which it becomes stealing OR 'stealing' vs 'not stealing' is insufficient to accurately describe a situation

It isn't just the author personally controlling though. It is about using tax payer's money to do so.