In his story The Pedestrian, Ray Bradbury continues to express his fears of humanity losing its "human-ness" in the future. This is a strong element in all of his stories.
One element required for this fear to become a reality is the loss of individuality. "The group" is always right. "The group" sets all of the standards. "The group" has the authority. "The group" will not tolerate deviation from its methods and preferences.
In The Pedestrian, Leonard Meade is different. Everyone else sits at home at night and watches TV, Leonard takes a walk. Everyone else prefers electronic entertainment, Leonard is an author. Leonard, because of his individuality which is what makes him "human", is one of the biggest threats to "The group". Therefore, on this last walk he is detained, arrested and removed.
The conflict is between Leonard and "The group". Between an individual and society.