From wikipedia's placebo button entry
A placebo button is a push-button that appears to do something, but actually has no effect, like a placebo. They exist to give the user an illusion of control.
Many walk buttons at pedestrian crossings in New York City were once functional, but now serve as placebo buttons. Many door close buttons in elevators are placebo buttons. Office thermostats may also function similarly.
Hey at least you don't have to ever fix these buttons since they don't 'work anyway :-)