it's usually both. things are not cost-effective, too many things happen at muni/county level, but of course at higher levels there's a huge backlog (due to lack of competence, due to low spend), plus the US is huge and sparse.

the "developed world" has a lot of problems with high costs (Baumol effect, extremely high standards, etc) and also the problem of low scale. China was able to roll out thousands of miles of high-speed rail at a very low relative cost, because of scale, a bit lower quality and lower standards (human rights, eminent domain, worker safety)

for example when it comes to policing the US pays comparatively less (given the rate of crime it has) even though it pays more than many other OECD countries

https://worldpopulationreview.com/country-rankings/police-sp... (see the police per 100K metric, for example France has 422 whereas the US has 242)