That's the way I think it works - I had to do that on a set of lights I thought had a camera (turns out it mustn't have been on as nothing came of it), but quickly weighed it up in my head of "several hours of BS arguing it for me" vs "someone might die".

Police cars will have dash cams, not sure on ambulances or fire engines.

That being said, scariest thing I did on the road was going through a red light to let an ambulance through at a motorway off-ramp. You better hope everyone else has heard those sirens.