Variable definitions of walkability

Steve Mouzon has an article up that describes changing walkability distances for different settings.  His category set comes, primarily, from the different transect zones. While it doesn't quite help me describe why the walkability distances are different in Newark than downtown Seattle (which look roughly the same on the map), it is an easy to understand concept that more planning and design students need to recognize.  And, weirdly, it would sort of suggest that you need more 7-11s closer together in suburban NJ than in downtown New Brunswick if you want people to walk there.