I am an American citizen, and I think you are spot on about isolation in this country. The dependence on cars is truly awesome and terrifying. It's something that is so dominant that I never considered it until I was diagnosed with epilepsy. I was disqualified from holding a driver's license, and so years ago I decided that I would try to live in the USA without a car. I did not consider that to be an absurd idea, but it has been very, very difficult, and sometimes not in the ways you would expect.

You'll see a lot of people disagreeing with your observation here, and they characterize it as an opinion, but it simply is not. The USA is insanely dependent on cars. If you live in the wrong place, it would be practically impossible for you to walk to a friend's house or to get groceries on foot. But I don't want to get bogged down in the obvious infrastructure issues; I think the more interesting disorder is the mental dependence that Americans have on cars.

Years ago I moved to a very temperate area. Low humidity, plenty of parks, lots of places within walking distance. I walked everywhere I needed, or, if it was out of the way, I'd take a bus. I would talk to people about my daily activities and found that everyone seemed to be repulsed by my stories of walking just a few kilometers. Friends offered rides non-stop and seemed very concerned that I would be walking for 20 minutes in 15C weather.

Live in your house, get in your car, drive to a strip mall, go into a business, come back out, get back in your car, repeat. These days, I can't help but view the typical car-bound American as a terrestrial astronaut who has to embark on Extra Vehicular Activities to survive. He manages, but every second outside of the conditioned environment of his ship, he is scared to death of the vacuum of nature.