I live in Arizona. Yes in the metro phoenix area there are a bunch of cameras on the highway. So of the other highways and few towns also have photo radar. There are signs giving plenty of warning you are approuching a photo enforcement zone. The trigger is you have to be going 11mph over the speed limit. That triggers the camera to take a photo. If your under that the camera doesn't do anything. The metro area also has photo cameras at certain intersection to catch red light runners. ADOT has a few freeway cameras to monitor traffic flow. They are not detailed enough to read plates or indentify people
My experience is going 11mph over the posted speed limit in the conjested areas is way to high. You should get a ticket anyway. The red light cameras are actived my sensors when you run the light. Experiencing some of the drivers in the valley, they also should get a ticket for running a light.
Basically, drive within the law and you have no problem with the cameras. If I was speeding due to an emergency. I would be willing to go to court and state my case.
The cameras have been set to 9 miles an hour over now, I guess they weren't getting enough money with over 3/4 of the ticketed people not paying the fines.