You're missing the outside of the rotor and looking at the vanes on the inside. I'd like to see some tech down at Pep Boys try to turn that thing!! "We finally got it smooth but its just a little below the minimum thickness!" I've never seen a rotor like this - probably wore the pad all the way down and then it was metal on metal!
I'm sure there's some unfortunate poor schmuck guy out there who's wife came home one day and said "you know honey, the trucks kinda been making a noise lately when I try to stop. Some of my girlfriends even noticed it today when we went shopping with your credit card. Its like the noise I heard the time I drove over a curb and knocked a hole in the oil pan and then ran the engine without oil, remember?"