I think geogrophy plays a huge role here. The land does a wonderful job of separating human populations and bending us to fit it's challenges.

Think of range wars here folks: One is apt to think that they're as entitled to a spring as the man who's land it happens to be on.

It's also harder to sympathise with somebody the other side of the ocean; we all have our problems afterall, and damnit, the kids are gonna miss the bus! Where are my keys?

People create all kinds of stresses and we like to blame them on other people.