Because Americans have a large and complex society, they take less interest in others.
But this is reinforced by affluence – the rich are generally indifferent to others anywhere - and a degree of genuine xenophobia, this last being quite apparent to outside observers in many events as in the recent ridiculous noise about a Spanish translation of the national anthem.
But there is also the deliberate influence of the Washington establishment. Americans are distant from their national government. Sometimes it appears as a Roman power ruling over a conquered people. This is a function of an outdated 18th century constitution and prejudices about central governments that have been there since the dawn.
The Washington establishment uses and abuses these attitudes. Take Bush's ignorant remark in 2000 about never reading the international section of the newspapers or the boast of a number of conservative congressmen about never holding a passport or stepping outside the country.
The really sad thing is that America's establishment starts so many colonial wars and follows so many questionable policies, and the people are virtually cut off from the process, just accepting it all as almost inevitable.
In effect in foreign policy, for all these reasons, America does not act like a democracy. The one-percent or so of the world's population active in American politics behaves like an autocracy towards the other 99% of humanity. They get no vote on matters deeply affecting them. How is this different than the role of the Chinese Communist Party - about 1% of the population - in China's internal affairs?
It's not.
