Fred Beneson:
As far as I understand it the GPL, (like most other licenses including CC, etc.) doesn’t require prosecution explicitly in the case of a violation of its terms, so much as it requires a cessation of distribution of the binaries or offending files.

Copyright law never requires prosecution.  It only allows for it.  Historically, GPL’ed projects have requested cessation of distribution or an opening of the source as out of court settlement.  The GPL cannot really require this, however, it can only specify the terms under which one can use the copyrighted work.  Thus, suing for damages is a right under law of the copyright holders on GPL’ed code when the GPL is violated, same as it is for copyright holders on All Rights Reserved works.  All other (more common) results are just projects being “nice” and handling out of court settlements.

IANAL. TINLA.