Don't know how it works elsewhere, but in the US you have a copyright whether you want it or not. If you do CC you still have a legally enforceable copyright. If you don't want it, you can put your work into the public domain - in which case everybody owns the copyright. But there still is, and will always be, a legal copyright in effect on any original creative work.
And yes, and CC has been successfully enforced in US courts. But it works in addition to the copyright. The courts have made it clear it doesn't replace it. And filing a CC does not mean you have a "legal right" to waive copyright. In fact, the courts have repeatedly said you can't waive it.
No, you can not waive copyright. You can not waive copyright and place your works in the public domain, either. That is not a legal option available to the creator. You are stuck with your copyright, whether you want it or not.
And as the article states, it doesn't matter if you decide to allow free use, promising not to sue. Your heirs, who will inherit your copyrights when you die, made no such promise to the people that are using your work, and might not decide to honor your wishes. As the new owners of that copyright, they have that right, especially in the absence of any proof of the creator's intentions, and even where proof exists (Woody Guthrie's anti-copyright notice and how there are plenty of people currently claiming and enforcing copyrights on his works, is a perfect example.). (Really, take the time to read the article, if you haven't yet. It raises some really good questions and makes some very good points.)
There hasn't yet been a case to test the validity of CC licenses in the long term.
There has yet been no case where an artist created a graphic and placed it on their website with a CC-BY license, then died. Then their heirs didn't pay the hosting bill and the site, with the statement by the artist that the image was CC-BY licensed, went away. Then 25 years later, one of the heirs decides to start suing everyone that is using the image, requiring everyone to prove in court that they had permission from the artist to use that work.
There hasn't even been a case to test the validity of a CC license in the short term, where some troll posts something on their site, slaps a CC-BY license on it, blocks spidering by archive.org's Way Back Machine, changes the license to CC-BY-NC-ND, then goes and sues people that used it under the older license...anyone that used it commercially or created a derivative work.
And there hasn't been a case yet where someone puts something on his site that he never intended anyone to copy, then along comes someone else who takes it, copies it, and slaps a CC license on it, then another person seeing the CC license uses it, only to end up getting sued by the original creator who never gave his work any such license*.
How will the courts decide in these kinds of cases is anyone's guess, at this point. We really can't make any assumptions here, especially in the absence of a hand signed document giving a specific individual specific permission for use. And this was my point in the other thread when I said:
Nothing takes the place of a document spelling out your rights under whatever license the creator decides to grant you, hand signed by the copyright holder. That document is proof of permission. Anything else, no matter how fluffy and feel good it is, is not a suitable legally binding substitute.*Technically, I could have sued a bunch of people based on a graphic that was stolen from one of my websites, for which someone stuck a portion of it in a scrapbooking kit, slapped a CC license on it requiring anyone that uses it to give them credit for it. I could have sued the creator of the scrapbooking kit, and anyone that used it, because I, the creator, never gave permission to anyone to use it other than for personal use as a desktop wallpaper. Any other use, by anyone, was unauthorized.