Wealthy suburbs are paid for by poor neighbourhoods.

Suburbia promises the best of both worlds - you get city levels of infrastructure, with rural levels of space. It's like glamping - you get to roleplay living on a farmstead, while also not needing to have a septic tank. In reality, though, city infrastructure is expensive, especially to maintain, and these suburbs produce functionally zero value.

In an actual rural area, there's farmland, producing value. In a city, with shops and workplaces alongside housing, there's value produced. In suburbia, there's just housing - and extremely low-density housing, at that. A mile of road, underground electrical cables, and sewer lines cost the same whether they're in a city center, or in the middle of an empty street, leading to a six-house cul-de-sac. To actually support this amount of infrastructure, serving so few people, with so little actual city revenue, property taxes would have to exceed median income - i.e., it's unsustainable.

To illustrate, here are the costs of services compared to city revenue, per acre, in Lafayette, with net positive in grey, net negative in red, as well as the average costs of different land use by area, in Eugene:

In short, these wealthier suburbs are a net drain on city economies, as they produce no value, but require exorbitant amounts of infrastructure and maintenance. In fact, these areas are functionally subsidised by the rest of the city, especially by higher-density, mixed-use neighbourhoods, which produce significantly more value for the same amount of city infrastructure. Poorer, urban neighbourhoods subsidise wealthy suburban neighbourhoods - and, despite being unsustainable, it remains literally illegal in most of the US to build anything but low-density single-family homes, due to car-centric zoning laws.

These suburbs are subsidised by the rest of the city, especially high-density mixed-use neighbourhoods, which produce significantly more value for the same amount of city infrastructure. Poorer, urban neighbourhoods subsidise wealthy suburban neighbourhoods, which are unsustainable - but it remains literally illegal in most of the US to build anything but low-density single-family homes, due to car-centric zoning laws.

Where it is legal to build anything else, including medium-density or mixed-use developments (as is the norm in the rest of the world), car-centric requirements for minimum parking, street setback, and minimum lot sizes make it infeasible, and again pigeonhole development into wide, flat areas of asphalt only traversible by car.

This is a new development, by the way - US cities didn't used to be like this, they were, actually, similar to cities in the rest of the world. It was a fairly recent development, that medium-density, mixed-use, walkable cities in the US were demolished, to build car-dependent sprawls.

You might notice that the majority of the land use here is parking lots. These parking lots, taking as much infrastructure and maintenance from the city as an actual neighbourhood with shops, homes, and workplaces, produce... nothing, except making it impossible to get anywhere except by car. When everything is spread out, with nothing but a mile of unshaded pavement between you and the nearest shop, of course you'd drive. When everyone drives, and the city's full of polluting, noisy cars, of course you wouldn't want to live there, and only visit in an enclosed, soundproofed box.

Other countries have gone down the same path of car-dependent development, and have been able to reverse course. Changing zoning to allow mixed-use is possible. City streets need to be torn up regularly anyway, and can simply be modernised when they're put back in. Amsterdam in the 70s was a nightmare of traffic and car accidents, and now it's one of the safest and most convenient places to walk, cycle, take the tram, or otherwise not have to drive. There are still suburbs, but there isn't suburbia.

All that's missing is political will - and as long as oil companies control the government, and some jackass car company owner can get your high-speed rail cancelled, then it's not gonna happen. But it can.