Without getting into politics (too much)... there are a lot of reasons for different responses between this hurricane and Katrina. Parts of New Orleans being below sea level probably matters a lot. Plus, FEMA was pretty clearly mismanaged then and doesn't seem to be now. I think those two factors probably account for more of the variation than the wealth of the inhabitants does, and I'm sure that I'm unaware of other important differences.

edit: "sea level" should read "water level"