Rudeness is becoming a signature of our (north american) culture and maybe others too, for all I know. There have been a few articles about it in the press lately (Macleans magazine a few months back). I bet if you google "rude" you'll get dozens of links to sociological publications. (I am referring to the rudeness we express towards strangers; the absence of public manners.)
In the case you mentioned, it may be simply group behaviour. In larger numbers, humans behave badly all too easily. Ask any waiter.
It may come from a culture of anonymity, a by-product of living in areas of large population like cities. The less chance there is of running into someone again, the less reason there is to be courteous. What's to be gained? Over time, more and more people behave this way until you reach a critical mass at which point there is no point being nice to anyone anymore. It's almost a statistical argument in the sense that as there are fewer nicer people around, there is less reason to be nice.
We live in a selfish culture I think. People figure that because they paid top dollar to be somewhere, and may not get there again, they just stand their ground and to hell with others. People like that often sleep in late though and then spend a long time giving the breakfast servers a hard time, so if you're quick you can be out and back before they show up to the site.