That is fascinating. None of my current stuff has been taken but I'm just an enthusiast, so...
The last link you posted, I noticed the author at least gave you credit. Still, kind of odd you weren't notified if that was the case. The others? Yeah. That's just wrong. If it's any consolation, the Misty Cove website design sucks; it simply doesn't show properly in my browser. (Chrome.)
Just one of mine. Years ago I had scanned a Japanese electrical outlet as reference for an Electricians forum.
Later in a Wikipedia reference, I found the picture where the culprit did a sloppy brush edit job on the frame to obscure the maker, but I could see where it looked an awful lot like the one I uploaded. It was later removed.
I don't know how much of a hassle it is to request a removal.
Photo hosting sites will let any member post without question, but if the owner sees it, he or she has to give ID and other proof that it's theirs.
On the other side of the coin Getty Images was infamous for sending out demand letters to anyone using their images, usually to someone who had their web design done in another country where the designer did not care where they pulled the images from.
I wonder if Getty was slapped over that tactic. I don't hear about it anymore.