Plenty of academic research/literature on this, as well as books:
> Chuck is not the first to point out the financial inefficiencies associated with sprawl. Robert Burchell of Rutgers[1] has led several important studies showing the substantially increased municipal costs associated with sprawl development; my then-colleague Matt Raimi devoted a well-researched chapter to it in our 1999 book Once There Were Greenfields.[2] At NRDC, we undertook a small empirical study[3] in Cleveland and Chicago that confirmed the additional operating and maintenance costs associated with suburban wastewater infrastructure when compared with that in the cities.
* https://www.smartcitiesdive.com/ex/sustainablecitiescollecti...
Strong Towns is only reporting what the literature is saying. You're free to be skeptical, but that's what they've concluded from the empirical evidence. The claim is falsifiable if you want to get into testing it.
Measure the cost of services per acre/hectare of low-density and of high-density, then measure the revenues. You'll see which is net positive and which is net negative:
> Urban3 is a consulting company that helps cities better understand the economic impact of development. They have worked with many American cities to better understand and visualize the costs of development, and uncover which properties are productive, and which are not. Some municipalities have been willing to share that information, and it has provided a fascinating glimpse into the financial problems caused by sprawling car-centric suburban development.
* https://www.youtube.com/watch?v=7Nw6qyyrTeI
Lafayette, LA case study from the video:
* https://www.urbanthree.com/case-study/lafayette-la/
* https://www.strongtowns.org/journal/2017/1/9/the-real-reason...
This is an accounting and ROI issue. If you don't want to believe the numbers… ¯\_(ツ)_/¯