I think it's more because America is huge and there's a lot of ground to cover. It's impossible for public transportation and private services to fill that gap.

I think people truly do not understand just how large the United States is. I've been on several family road trips with my wife and two kids all across the country, from west to east, north and south, and back again. The country is huge. If you're a young'un who's only ever experienced life in a city or suburb, you really have no idea just how big this country is.

china is huge yet most people don't have cars. It's not the geographic size it's because its population is spread out thin due to post ww2 american dream urban planning where we built rings upon rings of suburbs surrounding urban cars because we did not think of any of the negative consequences of everyone having cars (among other things)