I feel like I am missing something here, a mile of road in a rural area costs $1,500,000 to reconstruct? How do small towns afford to maintain their roads?? Perhaps there are many costs that don't inflate as the number of miles increases, like the equipment needed to break down and repave the roads?
Often, they don't. Examples:
https://www.strongtowns.org/journal/2010/1/11/the-cost-of-de...
https://www.sdnewswatch.org/stories/small-s-d-towns-struggle...
https://www.wpr.org/small-wisconsin-towns-paved-roads-return...
Many places in the US spent and borrowed to build infrastructure without budgeting for long-term maintenance; they also encouraged development patterns (e.g. suburban sprawl) that are cheap to build, but quite expensive when you take into account the long-term maintenance requirements.
This is a problem even in more urban areas, which is why lots of urbanists (including Strong Towns) advocate cutting back on new road construction, and taking into account the local tax base before building out infrastructure.
https://www.strongtowns.org/journal/2019/1/22/paved-with-goo...