the psychological concept behind what you're describing is called "diffusion of responsibility" http://en.wikipedia.org/wiki/Diffusion_of_responsibility http:/

the psychological concept behind what you're describing is called "diffusion of responsibility" http://en.wikipedia.org/wiki/Diffusion_of_responsibility http://en.wikipedia.org/wiki/Diffusion_of_responsibility apartment buildings have burned down because nobody called the fire department, assuming someone else would do it the entire time. when i was on a recent trip talking with a tour guide, the guide told me that they limit each group to around fifty people not because they can't handle it, but because they actually make less in tips in larger groups. the same applies here -- nobody tips because everyone assumes that the others will tip.