The article was about a proposed bill in the UK. Which is why my remarks were tailored for the UK.
So just to clarify it seems you are saying it is difficult to prove it is your work without a copyright in the US. Not that without a copyright you have no recourse. Am I understanding you correctly?
I guess you are making an argument for digital. Use your own camera and each image is automatically stamped with your name on it. Some of the fancier ones also include GPS information so if you shoot at your studio that is further proof the work is yours. I guess that is where part of the confusion comes in for me. All my images I've sold were produced electronically and have my named embedded in them and I keep the RAW files. With negatives and chromes its a bit trickier. I can see where things would be hard to prove. How do your register the copyright on negatives and chromes? Do you scan everything in and upload the files somewhere?