There may be a cultural component. A few very poor 1st-generation immigrant Dominican and Cambodian communities near me are actually super walkable (e.g. grocery store and schools within 10-15 min walk). Same with the much richer historic downtown. It seems that the white and 2nd+ generation Hispanic upwardly-mobile middle classes actually have the most car-bound lifestyle around here. Maybe being able to afford an isolated yet stroad-surrounded single-family home is kind of a trap in the long run.