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How is the creation and distribution of a derivative work not a 'use' of the software?
Lemur already answered this but in his own typical way of throwing a bunch of links and not being too coherent. So, I am answering in a way that hopefully even a layman would understand.
'Use' of GPLed software literally means using it in a personal environment, ie. you do something with it. Using GPLed code in f.ex. a software project you are coding is literally using it, after all you do something with it. It is a derivate work then but as you are not distributing it you are free to do as you may with it.
It's when you wish to distribute the application you wrote that the copyright law steps in: you have code in your application that is copyrighted to another party and you have to agree to their terms before you can distribute their copyrighted work. This is not 'use' of the code, however, this is literally distribution, and copyright law is all about distribution of copyrighted works.
If you make proprietary licenses invalid, you have to do the same for Free licenses.
Copyright is the only law that covers both sides of the software fence.
The copyright owners can grant/deny anything in regards to their work.
Them's the facts.
Incorrect. Copyright law governs the distribution of copyrighted works, not use. In most EULAs in proprietary software there are lots of clauses how you can use the software and how you can't, but such clauses do not belong under the copyright law and are invalid in most countries. Of course, the parts where EULA says you are not allowed to copy the software to others etc do fall under copyright law and those parts are valid.
Then again, selling a copyrighted work as a whole, not parts of it or copies of it, belong under sales law; it's not distribution, it's the copyrighted work changing owner from one to another with the aforementioned party losing their ownership. EULAs cannot dictate how sales laws applies to them and thus all such clauses are again invalid. And before you jump to conclusions: no, it's sales about the particular work, not the copyright of it.
(I'm starting to think that it'd be easier to just write a complete article explaining these things than just repeating the same things in comments section every time someone who doesn't understand what he's talking about makes erroneous claims..)