The difference in rich and poor neighborhoods is visually apparent, as shown by Tim De Chant:
Here is a comparison of west Oakland, CA vs Piedmont:
More visual comparisons at the link. Jess Zimmerman comments, with several additional links: "Since trees increase property values, this is a classic case of the rich being given whatever they need to get richer. And considering the other things trees do for us, it’s also a case of the rich getting to be smarter, cooler, and have fewer allergies."