If you come across one of these whilst you're out and about, it's reasonably safe to make a few assumptions; you are on foot, you are trying to cross a road, and you know what these do.
I've not yet been to a country that doesn't have a similar system, but I think ours is the only country that has to spell out exactly what a red and green person mean every time someone encounters it.
Seeing as they were introduced nearly 50 years ago, I think people probably get it by now. So not withstanding the need for the little rotating knob underneath, and a wait sign (to acknowledge the button press), couldn't we trim these down a bit?