Here in DC area we have them on the smaller streets and intersections.
I am a victim of intersection "red light" camera. When you cross intersection on the yellow light and you if you haven't pass the street then it will take picture of your car. Acctualy 3 pictures. First one on the intersection with the speed, time and visible yellow light. Second picture of your car still in the intersection and the red light visible. And the third picture is a close up shot of your registration plate
It cost $75 but it doesn't count against your driving record.
Speeding radars are mounted on the streets with speed limits between 25 and 45 miles per hour. The well known radar camera is mounted next to Gravelly Point, right next to entrance to this spotting location. It will take picture if you are going 19 miles over posted speed limit, so in this case you will get picture if you are driving 64mph. And the fine for it is $150.
To my knowledge, there are no speeding cameras on Interstates in USA. All of this is done manualy by damned troopers. (I am also a victim of this thing - I was cought 5 times hehehe)