In this shot from one of my favorite films Eternal Sunshine of the Spotless Mind, the film's main character Joel Barish played by Jim Carrey waits for a train to get him to work. To me this one shot perfectly sets up who Joel is as a character at this point in the film. You can barely even see him in the shot. I believe this is done to show that the character feels unimportant and just part of the crowd. It sets up the feeling of being lost among the world he no longer feels part of.