Someone walks up to a lift, sees the button already lit, and presses it anyway. They know it has been pressed; the little ring is glowing right there. The lift heard the first time and will not come any faster. I don’t think the press is for the lift. It is closer to signing a birthday card that everyone else has already signed: the card would arrive just the same without your name, but then it wouldn’t be from you. Waiting is easier once you have put your name on it.