For pedestrians: In my city I have yet to find a bogus one. They are there to control traffic flow. You press it, you get a green light. You don't, you can die waiting.

It's there to allow the priority traffic to be interrupted only if necessary.

I believe I heard something like "press a button for a faster signal", but that doesn't make any sense at all.

Municipalities want to control the traffic in the most efficient way. Not to give any troll a button to break things.

However there are several places where there are e.g. sensors to allow for a favourable signal for drivers. But then again that is mostly in places where they would wait for a green light for a long time.

The theory and practice in the transportation field is quite interesting.