> I would guess that most suburbs are financially unsustainable in the long term because they pay less in taxes than it costs to maintain their infrastructure.
Again, that is something that might be true for some places but not others.
I know of suburbs that definitely pay for themselves. And it's not hard to see why -- the property taxes are high and many of the residents are paying high income taxes too. Plus, many residents of suburbs commute to work in cities, where they contribute to the success of businesses that pay taxes in those cities.
I also know that some of the new subdivisions outside of Sacramento have paid for all of their infrastructure via their HOA, so that all of the money to build and maintain the roads, sewers, and power lines was 100% paid for by the homeowners. That's also apparently a common model for new housing in Nevada.
These arguments about taxes are also a form of special pleading that we don't see much of in other debates. Taxes are redistribution. Quite a lot of people and organizations get more in benefits from the government than they pay for, e.g. welfare recipients and students getting grants, companies get subsidies, state governments move money around to pay for schools, etc. Nobody seriously argues that the police and fire departments should only serve people who pay income tax, or that people without children shouldn't be taxed to pay for schools. Yet for some reason people seem to think that suburbs should have a unique requirement to pay for themselves 100% and can't be sustained if they don't.