Dumb question: how do these systems distinguish a traffic light? Here in New England at least, there's quite a variety of lights, many different modes (red, yellow, green, flashing red, flashing yellow, no-turn-left red arrow, no-turn-right red arrow, and different light technologies: old-fashioned style, Fresnel lens, slotted shade. Add to this complexity the weather conditions. Suppose the sun is shining straight a…
red, yellow, green, flashing red, flashing yellow,
no-turn-left red arrow, no-turn-right red arrow
You forgot flashing green, which does actually exist, at least in MA. You treat it like a green light, but it could go yellow and then red if a pedestrian presses the walk button.