What about situations like the last plane out of a war zone with a limited number of seats? I think people tend to become less charitable then? Or if scarcity really hits?
I remember specifically an issue in Europe a couple of years back where a series of snow avalanches was destroying hotels and killing people (in the alpes, I think - hotels had been built in illegal places). Roads were blocked and the only way out were helicopters. Supposedly there were some ugly displays of selfishness around getting on the helicopter first.