I spend dozens of hours a year driving through the rural South. So many towns as you describe. And I have no idea how they're alive at all.
A weird thing I've seen: Most small Alabama towns are quite charming and well kept. How does that work when there's no obvious economic driver?!
Cross the border into Mississippi and it's a different story. You could teleport me to a random highway or town and I could tell you whether I was in AL or MS.
The wealth gap is on full display everywhere. You'll see a stunning property and home, rambling across several acres, and then a couple of trailers so beat down the county would condemn them if they cared to look.