User Story

Hidden assumptions and implicit requirements

I was going home and I was walking through the lobby in direction of stairs leading to underground parking. Next to the stairs there is small lift. I think the lift can carry 3 people with some luggage. When I was approaching the stair, lift went from the parking to ground floor and the door opened. The view was quite unusual, because I saw a guy sitting on one of these self-propelled cleaning machines. Now, if you would like to go into business of cleaning machines, would you think about requirement specifying that this thing needs to fit into small lift? It wouldn't cross my mind.