David, walking to work is not healthier than driving when you choose to commute into the city (whether to avoid confiscatory municipal taxation, avoid higher crime, avoid higher noise pollution, be better able to view the stars at night, etc.), nor is it healthier when you walk in freezing temperatures, in inclement weather, in excessive heat, as well as along highways and near high-crime neighborhoods and remote locations.
What studies like these miss are the health benefits of the wealth effects of being able to drive to places (time is money), of being able to avoid illness, injury, theft (the term “highway robbery” wasn’t always just a metaphor), and stress, not just in one’s commute but also in one’s choice of neighborhood.
