Understanding other cultures is hard. Tolerance seems even harder. Why?

Judging by the amount of intolerance displayed by various nations / factions and the fact that last century we've had two world wars, it's almost miraculous that WW III hasn't broken out yet.
Pity that the clash of points of view escalates into violence much more easily rather than evolving into understanding and synergy. It generally takes much more energy / effort / patience / compassion / courage to understand a different point of view / culture and appreciate it than it does to deny / reject / oppose it.