I'm challenging one of these right now. Yes I did it. I was late for work and there wasn't another car in sight. I stopped, checked and rolled. None of the pictures (3 of them) show the driver. If they can't prove operator then they can't issue a moving violation. They have sent me two letters and I just deny it was me driving. They asked me to identify the driver and I denied positive knowledge. I talked to a traffic attorney and he said this was right. I can't say they aren't affective at slowing down traffic though. As a local FF we've seen reduced incidents at camera'd intersections.
My worst day of fishin' is still better than my best day at work!