That was my point, how do you know whether it is an actual emergency? Too easy to just turn the sirens on for long enough to go through a red light and none of us would be any wiser. Sure, we could report every cop, fire fighter or ambulance driver who ever did this, but when one considers the time and resources required to check whether every running of the red light was a genuine emergency, it's hardly worth bothering, is it? As Jasbike said, if they're not endangering anyone, why worry about it? Personally I'd like to see something done on the dickheads who run red lights everyday in traffic who are endangering people.