Not every camera is an ALPR. The ones mounted above the signal heads like that are for computer-vision-based vehicle detection for signal phasing and timing (i.e. as an alternative to an inductive loop). AFAIK they're only hooked to the traffic signal controller and don't really provide video to any external system, but even if they could, they're not pointed in the correct direction to be able to capture the sort of information an ALPR does. The cameras on top of the signal heads mostly just see the roofs of the cars, while ALPRs are mounted a lot closer to the ground so that they can image the fronts and backs of the cars and capture stuff like the license plate and the driver's face.
(Source: am a former traffic engineer.)