So should copyright laws that protect GPL software also be removed?
GPL can only exist because of government regulations and action when those regulations are violated.
I guess If copyright seized to exist you could take GPL code and modify it without sharing back, but the users would also not be required to pay you for using it, so…
also GPL is mostly trying to fight closed-source code which is just as possible without the current copyright system, it can still be kept private like any trade secret. GPL relies on the system to force releasing source.