Many traffic lights are actually placebo buttons. They do nothing at all when pressed.

With the advent of computerized traffic lights, the walk light will go on automatically, without anyone pushing the button. More specifically, in New York City, new walk lights don’t even have buttons to press. Of the 3,250 that still do, only 750 have buttons that actually do anything. The remaining 2,500 buttons have been deactivated years ago. People still press them anyway to feel like they are in control of the situation.
(source)