It's not simply because "they can," but that the towns and cities get built so that things are distributed and not served comparably by bus lines. For example,

It's not simply because "they can," but that the towns and cities get built so that things are distributed and not served comparably by bus lines. For example, in my median-density medium-sized city, by USA standards, my grocery store is 16 minutes away by bus, but 5 minutes by car. A coffee shop I'd go to is 29 minutes by bus and 6 minutes by car. Things are much worse for where >60% of Americans live too...