Most places by land area, sure.

But many, many people live within a metro area that has at least some pockets where being car-free is feasible. For cities like New York, Chicago, DC, or San Francisco, those pockets are pretty large and cover a large population.

Growing those neighborhoods by population and size is part of the overall strategy for reducing car dependence. Even in heavily car dependent Houston or LA, there are mixed use developments where people can live and grocery shop and dine and maybe even work without needing a car. Obviously that's not going to work for meeting up with other people from the same city, but living in a neighborhood like that can reduce the typical number of weekly car trips for a typical household: whether the young kids need to be driven to a playground/park or to school, whether a visit to the grocery store or gym or bar or library need a car, etc.