The setting is the antagonist in "The Pedestrian" against whom Leonard Mead, who loves physical and social activity, finds himself in conflict because there is a complete lack of physical and verbal socialization in his cultural desert of a neighborhood.
That Mead has met no one in ten years as he walks outside on the sidewalks is suggestive of the complete lack of activity on the part of the residents of town, as well as their total disinterest in the outdoors and nature. As he traverses the neighborhood, Mead wears sneakers so that no dog will bark to alert anyone that he is outside since no one ever leaves the house in the evening. Consequently, they may believe a vandal is outside.
Instead of going outdoors or visiting a neighbor, the inhabitants sit before their television sets, mesmerized by the programs and fantasy world contained within:
The street was silent and long and empty...If he closed his eyes...he could imagine himself upon the center of a plain, a wintry, windless Arizona desert with no house in a thousand miles, and only dry river beds, the streets, for company.
This milieu created by Bradbury conveys his theme of the depersonalization and disconnect that technology effects in modern society. Within this setting Leonard Mead is ironically the anomaly; he is judged a threat by the robotic police car and arrested. Thus, it is the setting which establishes the conflict in Bradbury's story: The new world of technology as a substitute for human relations comes into conflict with the man who yet believes in physical activity and contact with other people.