That's true of all rear-ends, but for the ones that are influenced by the presence of a red light camera, it must also mean that the crash wouldn't have happene

That's true of all rear-ends, but for the ones that are influenced by the presence of a red light camera, it must also mean that the crash wouldn't have happened without a camera-induced behaviour shift in the leading car. So it requires not only an unsafe following car, but also the lead car going too fast towards a yellow and then braking suddenly, upon remembering that they'll lose money for going through a red light. Still the fault of the car in the rear of course, but if the car in front is driving reasonably in the first place, then the red light camera won't have any effect. The ones who get rear-ended are the ones who were going to anyway, camera or not.