You get to use GPL'ed software on the condition that the community get your modifications and/or
the software that links to it. Sounds fair to me.
I think I get the point of open source software, which has a lot of great aspects, but I'm not sure about fairness.
One of the issues I see with it is that there is no concept (that I know of, but I'm certainly no specialist of GPL) of proportion, which I personally think can't be separated from the concept of fairness.
One example (very frequent in private companies) is the following: let's assume you just want to use one GPL library in your product, mainly because it's robust, proved and reasonably supports some standards. The fact that you would have to give away your whole software source code, which is probably a lot more than just a library, is often not fair. It's not in proportion of what you took. There may be some tricks to circumvent that (such as isolating your software in pieces and make sure there is only one small module that uses the GPL library), but I don't know if it's a valid approach according to GPL at all.
In a world where there is absolutely no economic competition of any sort (which is not our world obviously), that may not be an issue at all. But this is not the world we currently live in.
This pushes most private companies to either not embed GPL-licensed software, violate the GPL license, or write all of their software modules in-house (or buy commercial licenses).
For GPL software backed by some institutions, there are sometimes commercial variants of GPL software that you can use freely in a commercial setting if you pay for it. That's a partial answer to the above issue but twists the spirit of GPL in a weird way.
Again, I get the point of open source which is supposed to encourage free sharing. But there are cases in which fairness is hard to justify.