UPDATE: This from A Train Driver Lost somewhere in EMT-land...
Pointless sign #11 isn't *entirely* pointless - in the areas of EMT-land where passenger intelligence is best described as limited, it can be almost embarrassing watching the darlings trying to open the doors by thumping the glass, kicking the body of the door, swearing at it or merely looking bemusedly at it because it hasn't magically opened for them.
Having a little sign pointing out that there's a nice button to press helps - at least for those who can read...
Nice to know our efforts are appreciated by the Eye though! ;o)