[zhdc1]

It's a very US-centric perspective to assume that density = cities.

Almost every town in the US, at one point, was dense enough to support a vibrant main street. Many (most?) of them even had tram lines and other forms of public transportation.

It's not an either or proposition. You can have cost-effective infrastructure through relative density without having to deal with all of the trappings - good and bad - that come from a city.