Some cameras only produce a photograph. Some produce a video with the light status showing on it--but there have been cases that's wrong, the camera recording what it was programmed to do which didn't match the real lights.
You need actual video of the scene that can be examined and which is of sufficiently good quality that the identity of the car can be confirmed. Very often it does not exist.
Likewise, speed cameras should record enough that one can do a time/distance calculation to confirm the speed--because the system can be miscalibrated or can be fooled by large, flat surfaces.
Or look what has happened with breathalyzers. Last I heard if a judge grants the discovery request for the source code the case gets dropped. And the whole thing is based on a flawed principle in the first place: the ratio of breath alcohol to blood alcohol varies substantially between people--setting it for average isn't accurate. As a screening test for doing a blood draw, fine, but it should not be allowed anywhere near the courtroom. (Some states get this right, some do not.)
And, yes, ambulances. I forgot about another time I know I ran a red light. Something with lights/sirens was coming up behind, no lane was empty, I was in the only lane with one car. Lots of space at the intersection, I pulled forward and turned hard right, clearing my lane without actually entering the cross path.