This is just silly. Before asking for double blind experiments or other types of scientific proof, one needs to first apply some common sense? Did the author ever live in a low density and a high density environment, so they can compare?

I did. Or rather, I lived in a high density (3500 people/sqmile) and I'm currently live in an ultra-high density area (45000/sqm). I used to have a car, and now I don't. I can now find most things I need within a distance of 2 to at most 3 blocks: the elementary schools my kids go to, grocery, pharmacy, movie theater, mall, gym, playgrounds, parks, a ballfield, gym with pool, liquor store, a few restaurants, a few docks with public bicycles (Citibikes), a bookstore (Barnes and Noble), a department store (Target), quite a number of cafees, etc, etc. In the past, whenever I needed something I would hop in the car and drive 5-50 minutes, get the thing, and drive back. Now I just cross the street.