Why do many Americans believe that America is the only free and rich country on Earth?

I'm a US citizen, think America is a great nation, I'm proud of her, we're there to help, we're generous and we attract people from all over the world and we've accomplished enormous feats, but I also recognize that we have allies, particularly Britain and Australia, as well as several other countries. Now I spent some time in Australia, and while I love America, I think Australia has a lot to be proud of as well: high per-capita income, long life expectancy, great infrastructure, etc. True, they never put a man on the Moon, but they've done a good job of attaining one of the highest standards of living on Earth and they also have freedom of religion, embly and speech as we do. So why do so many of my fellow Americans believe that America is the only country on Earth with freedom and prosperity when several other countries have it as well? Canadians aren't suffering from famine and being thrown into gulags for disagreeing with the Prime Minister; New Zealanders are not coping with cholera on a mive scale, political executions, the majority of its citizens living below the poverty level, so where does this mentality come from? And why is it considered impossible by some to compliment a prosperous ally of ours without being accused of being an "America hater"? Just because you recognize that another country also has several admirable features does not mean that you hate America, and need to get out.