Per mile, small urban roads were millions of usd a mile (see department of transports annual report and it varies by region). Maintenance is even worse. It’s the 5th highest expense for most cities (US census survey of local and state governments 2020).
Of course the suburbs don’t make sense, you have a half mile of road out to a neighborhood and another half mile of street in the neighborhood itself. The percentage of property taxes going to the road is probably just a few percent points. With only a few hundred houses, it would take decades to raise the 1-3 million to replace the road.
Already have this problem with our subdivision lol. Private road, and replacing the road is going to be $20k a house even over 20 years or something even with a bond lol, and that’s a normal, reasonable-density subdivision. People don’t realize how much rural and suburban roads are getting subsidized.
Initial infrastructure is often paid for with up-front cash transfers from the federal/state government and long-term loans, then the long-term maintenance is supposed to be funded by local taxes but in many cases is set up to be more expensive than the long-term available tax base, so infrastructure just starts falling apart and then either taxes go up or maintenance is put off and people left holding the bag are screwed, or external cash bailouts make up the difference.
In either case, the suburbanites (especially near the beginning of the construction cycle) and initial construction companies are getting a huge subsidy from everyone else (and from future generations) to promote an inherently unsustainable and destructive living arrangement.
It's a kind of Ponzi scheme, and like any other Ponzi scheme, at some point the music stops and then the whole system is in an extremely precarious place.
