How is the GPL enforcable? If you download code from Github, the copyright holder can restrict your usage, up to and including prohibiting anyone from using it. It's silly to conflate digital works with physical media, copyright properly refers to a creator's right to control and potentially profit from their intellectual property.
edit: I find it funny that on one hand, when 'stealing' comes up, people who reject IP law say 'but it's not like physical objects, they still have it'. Then when licenses come up, it's like 'finding a book on a bus'.
The GPL is enforceable in that it doesn't try to prevent anything. Using it merely means you share title in your derived work.
This (having GPLed code laying around) is a 'found book' scenario. You've got a copy that you didn't violate copyright to make, thus it's legal to use.
EULAs are a non-copyright attempt to control this usage. They used to be based on the idea that any and all copying, incidental or otherwise, was prohibited and thus to use software (and copy it into memory) you needed a license. But this has been specifically denied in current US copyright law.
Blanket permission is now given for copying where it's an inherent part of using the work. This supports the idea that usage is generally unrestricted (unless you or your agent acquired this specific copy by license). Which makes sense; they'd have called it UsageRight instead of CopyRight if they meant that.
Now EULAs are (usually) based on the Uniform Commercial Code but that requires a contract (of sale) which can, of course, only be binding on the original parties and their agents.
So again, why would a EULA be enforceable on software a user found?
As for forum humor, do you know what I find funny? It's when someone takes caricatures of different people's views on different topics, conflates them, declares them inconsistent, and shoots down an unrelated argument based on this trail of "logic".
edit: I find it funny that on one hand, when 'stealing' comes up, people who reject IP law say 'but it's not like physical objects, they still have it'. Then when licenses come up, it's like 'finding a book on a bus'.