I think you are confusing the notion of a work being copyrighted and the notion of someone complaining about any infringements on their copy righted works in a

I think you are confusing the notion of a work being copyrighted and the notion of someone complaining about any infringements on their copy righted works in a court. The first is indeed more or less automatic. You can't actually opt out of copyright. It applies to any work that is created. With very few exceptions. Hence copy left licenses, which try to undo some of the restrictions that copyright impose. Likewise the notion of putting something in the public domain is a bit tricky under international law. It's not clear what that means everywhere. An explicit license is better. The second bit (enforcement) can be done by the copyright holders. Or, as is common in e.g. the EU by organizations like GEMA that actively charge third parties money for playing music in public. That's a weird one IMHO. The money does not actually go to the rights owner but to big owners of music rights and other members of GEMA. So they benefit from other people's work through some weird legal construction that gives them the monopoly on exploitation rights for that sort of thing. But basically, unless somebody goes to court nothing happens. That's not automatic. Trademarks are a completely different can of worms.