Regional balkanization has a lot of issues; not only are poor areas left with few resources and projects lack coordination and get expensively duplicated, but also they tend to compete with each other to offer tax breaks to companies, and in the end the region gives a big tax break to a company that most likely would’ve located somewhere in the region anyways.
The Corps got it running in a couple days. It was incompetence that caused the problem, and I doubt you will argue that poor people are less smart.
And yes, Flint's water crisis was absolutely connected to a lack of funds. It was directly precipitated by the city's declaration of a financial emergency[1], which in turn caused the city to seek cheaper water sources.
[1]: https://www.mlive.com/news/flint/2011/11/former_acting_mayor...
It's not a "smart or not smart" thing: wealthy areas demand (and receive) adequate attention and funding for their public utilities. Incompetence on the municipal level is a symptom.