|You mean these don't work?!|
You might be thinking, What?! I've been fooled all these years! Well, hate to break it to ya, but it's true. In today's world, computer-controlled traffic signals have made these kinds of pedestrian push buttons pretty much obsolete.
Although most of the push buttons that you see around cities like New York City don't actually work, the Department of Transportation has left them as part of the street landscape to serve as a sort of psychological reprieve for city folks who might think that pushing the button might help speed up their pedestrian journey.
Still, a fair number of push buttons actually do work at street crossings where the "walk" signal might never light up if the buttons aren't pushed, so perhaps it isn't really futile.