Actually, having worked in a traffic engineering department for a while, those counters are meant for pedestrians. The were trying to figure out how best to hide the count from the cars. Why you ask? We all know how awsome drivers are, and do you really want them fixating on that timer going down, them pushing more on the gas to make it, and paying no attention to the rest of the intersection?
In short, the counters tended to increase the number of red light runners.
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