A large part of that is because traveling abroad is prohibitively expensive for a lot of people (which the article touches on). Especially if you don't live on one of the coasts. California to London is over 10 hours of flight time. I don't think Europeans fully appreciate how huge the United States is. Texas alone is bigger than every country in Europe, save Turkey.
The U.S. is a huge country and most people have little desire to sit in a cattle-car (airplane) for 8-12 hours. A 12 hour drive to Florida is much more palatable for most people than a 12 hour plane ride to a country where they don't speak the language (typically.)
Which I guess begs a follow-up question: why aren't they more outward-looking? This is the question the article asks halfway through, but it still ends without much of an answer.
As someone living in Ireland, where many things are of similar low quality (e.g. healthcare), we are outward-looking but only in one specific way: we look toward the US for a lot of things. I've often asked this question in a different way: why do we look to the US and not elsewhere (e.g. the UK, France, other EU states, where healthcare is actually ok). The two answers I've come up with are anglophone bias and anti-English sentiment arising out of our history, only one of which applies to the US, and yet they definitely don't look too us, to Canada, to other anglophone countries. So I suspect I'm wrong on this explanation in both cases...
Yes, of course other countries, but most Americans have limited understanding of the way of life of people in other countries. Points of reference exist but the majority of Americans aren't familiar enough with those points of reference to make a comparison.
