That doesn't mean it is easy and convenient, or even always safe. Often enough, people are walking in places that were not planned or designed with pedestrians in mind. Problems notwithstanding, the "walkability" of these places is a fact defined by their very usage.
It is precisely by identifying places where people walk, despite seemingly undesirable conditions, and then observing how they do it, that we can better understand how to make places where people will walk. By focusing on these locations, we also have an opportunity to improve conditions for the people who already depend on walking there while making it more attractive for even more people to join them.
One fascinating indicator of pedestrian activity in suburban-style development is what I refer to as "desire carts." They're odd clusters of shopping carts on the far edges of parking lots. These shopping carts accumulate where people leave them when continuing on foot.