I can see why ppl don't carpool and ride the bus: it's seen as declasse, you're too poor to afford something better. Gotta have money to make money. Riding the bus, I get the impression so far, is seen as someone who's "not professional". Christ.
[WS:] Maybe it is about money too, but in my experience it is more about security and stupidity and perhaps fear too. First, many (if not most) US-ers I met are obsessed with security and feel very uncomfortable in public places where they have to interact with other people, especially those who look different. Cars, otoh, insulate them from others thus giving them a sense of security.
Secondly, taking public transit requires thinking - planning ahead and figuring out your way. Many US-ers I have met are seriously challenged in both departments - they cannot plan and easily get lost in unfamiliar environments. Driving, otoh, is a simple routine, and once memorized, it does not require any thinking and figuring out. In the same way, these folk prefer organized tours and cruises fro which they pay through the nose instead of going on their own for much less.
My understanding is that "average" US-ers feel they would be eaten alive three times without even knowing what hit them if they stepped outside their familiar "lebensraum" - their suburban McMansions and their cars (or their hotel and English-speaking enclave while abroad.) So they tend to stay in their cocoons, for which they pay through the nose, afraid to step outside. It is more about fear than money. Of course, not everyone is like that, I am talking here about a certain tendency within the so-called middle class.
Wojtek