How does Anders invoke the idea of justice within the scene of the robbery?

Anders hears one of the robbers tell the lackadaisical bank teller that she had better get back to her station and get "her ugly ass in gear" (12). Anders then turns again to the woman in front of him who had complained to him about the teller earlier. He says, "There you go...Justice is done" (13), meanwhile paying no attention to the growing anger of the man with the pistol.