But to call NYC, LA, Philly, Chicago, Minneapolis, Houston, etc sparse doesn't seem very accurate. Yes, LA is vast, but I wouldn't call it sparse.
http://www.demographia.com/db-worldua.pdf CTRL+F for "BUILT-UP URBAN AREAS BY URBAN POPULATION DENSITY: 2025"
America is the exception for population density in general.
Busses go places I care about: two blocks from my work, and to the airport.
My US city is dense. Not like Europe, but unless the argument is that major metropolitan areas in the US are not dense enough (LA?), I don’t buy it.
Bus transit has problems, but I don’t think it’s as simple as the parent is asserting.