I notice a lot in London that there are a bunch of pedestrian lights in areas witha steady flow of traffic that will only work if the button has been pressed, yet every single day I see people, often the same people, stand there until someone else presses the button.

Part of me wonders if there's almost an aspect of not wanting to cause offense involved. If you're the person who presses the button, you're responsible for the ire of whatever drivers you delay, so you'll either wait for an gap to run across the road or someone else'll press the button and absolve you.