First off, love your username. Do you still have that bicycle license plate?

Second, life expectancy for poor people is not just related to the amount of exercise they get. Infant mortality, manual labor, and violent crime all have a much higher impact on poor people than well-off people.

Add in poor diets (because junk food is cheaper than healthy food) and genetic predisposition to some diseases by historically impoverished segments of the population and it’s a recipe for shorter lives.