Those cameras serve the same function as the push to walk buttons or the loop detectors that you see cut into the pavement at other intersections. They let the traffic control system, housed in the box near the intersection, know there is a vehicle present. Normally all the cameras at an intersection would be pointed at different locations within the intersection simply because its cheaper. Certain locations could, because of site specific requirements such as sun glare, justify additional cameras to ensure they function properly.
While it could be possible to configure an intersection to store or transmit those images, I doubt that is happening on any wide scale basis. I say this because there is not a specific reason to store them in the controller, and the amount of additional bandwidth to send them off site (x number of cameras per site by y number of intersections) is a cost that most agencies (State DOTs, County Road Commissions, etc.) either can't or don't want to bear.
Red light, toll plaza, and speed cameras on the other hand do need to record and store images, but they either generate or prevent (in the case of cameras at a toll plaza) revenue that would cover the additional costs associated with them.
I'm a former civil engineer, however most of my experience with traffic control systems occurred during my undergrad work. My work experience involved bridges, part of which involved remote monitoring systems for them and there is a bit of overlap there.
