Why does U.S. society cling to the suburban model despite its inefficiency, unsustainability, and many social ills?

The reasons are momentum, government policy, and land availability.

American society is invested in the infrastructure of suburbia. Putting aside new development, most places don’t have the concentrated development to support viable mass transit (if they have any at all), so if you live there already, you need a car. Everyone has a car, so the infrastructure of the community needs to support that, from roads to parking lots.

It’s hard to ignore the fact that in the United States, there’s still a lot of land available for development. The Economist somewhat flippantly described the US as having “unlimited land” in a leader a few weeks back. It’s hardly unlimited, but if you want to develop land, it’s there to be had.

As for why we don’t change this, there are a lot of reasons, but the explanatory ones have mostly to do with government policy. Contra the idea that suburbia was a phenomenon of the market, federal and local policies have driven the growth of suburbia for the better part of the last century. Just follow the money for housing and transportation.

From the 1930’s (with the creation of the FHA), the federal government has been in the business of subsidizing home purchases, incentivizing people to buy rather than rent. Early FHA policies were limited to new development and in some cases actually excluded housing in racially mixed neighborhoods. Both of those policies led to new suburban development.

As of about 10 years ago, the US federal government spent ~85% of its transportation budget on highways. The highway funds are paid through an autonomous funding mechanism, making it difficult to dismantle.

Claims about things like the quality of schools are based on earlier policies. The quality of public schools is usually related to revenue base. So school funding will follow incomes further out from cities. I recall, too, that early 20th Century laws in the US diminished cities’ ability to annex the developing territories around them, thus halting the growth of their income bases to pay for such things.

There are cultural reasons that people want their own home, but government subsidies reinforce the desire to own a home. If you value owning a home over where you live, then you buy where you can afford (counterbalancing issues like transportation cost and quality of life are rarely considered in this calculus, if you’re wondering).

See Laws of the Landscape by Pietro Nivola for more on the policy details.