True, that's even spelled out in the GPL itself (that's from GPL 2, but GPL 3 has similar content in section 9): > 5. You are not required to accept this Licen

True, that's even spelled out in the GPL itself (that's from GPL 2, but GPL 3 has similar content in section 9): > 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License [...] The copyright owner obviously doesn't need the license to have permission to modify the code, so they're not bound by it.