"Why can't the Arab nations unite"? I am having real difficulty understanding the question or, I should say, why it is a real question anyone feels has a reasonable answer. One may as well ask, Why can't the European / western / eastern / African / Asian / Christian / Islamic / Buddhist / etc. etc. etc. nations unite. They don't unite because they live in the real world of split vested interests, misunderstandings, wilful mongering of many sorts, historical legacies that become mantras, etc, etc. In other words, they behave like human beings have always done. Welcome to the real world.