[rz2k]

You are right, but in practice you have to deal with the repercussions of inspiring leaders among the waiting crowd to police your actions. Going down to the 17th or 16th floor and catching the “up” elevator might not get as many glares.

Where I’ve seen this happen is after speaking events in the university clubs near Grand Central Station in New York. The complete dynamics of the situation probably involve a minor risk to social reputation, and some people playfully trying out game theory to amuse their friends.