> There's nothing to stop you contradicting yourself by indicating a different direction of travel. Which makes you wonder why you had to indicate the direction

> There's nothing to stop you contradicting yourself by indicating a different direction of travel. Which makes you wonder why you had to indicate the direction in the first place. You had to indicate the direction in the first place because the system can give you a cab that's already going in that direction. Even if nobody is in the cab it may be going to another floor that someone has pressed the call button before you. If you press a button for the opposite direction it will still go in it's original direction. Eventually it will change direction and go your way but that just ensures you'll spend the maximum time in the elevator. During your ride in the wrong direction another cab may have freed up or there could have been one already free but a few floors further than the one going in the other direction. That's also why elevators have the up and down lit arrows at the top of the door to indicate which way it's going. This keeps you from getting on one going the wrong way if it come to your floor first to either drop off or if both call buttons were pressed.