Claiming that "everybody in the US has a car" is just another way of saying "I have absolutely no idea about how people live". One educational aspect of bicycle touring in the US is that one gets to know hitch hikers and vagrants of various sorts. Meeting people literally on the road creates a sense of camaraderie and fellowship which I am not going to exaggerate, but which is still noticeable.
Ray (above) was a soft-spoken gentleman I met 2002 on the side of the road in Arizona. He had access to some form of free dental care (which he quite needed) in another town but had access to no motorized vehicle, and there were no public transport alternatives between the place he lived and his dentist. Europeans never believe me when I tell them this, as they are not only convinced that "all Americans have a car" but also have absolute faith that surely "Greyhound or Amtrak" must connect every populated place in the country with every other populated place.
So Ray got around on his bicycle and had made a his own trailer, complete with a beer crate on top for his small terrier mutt.