How does class structure in Maycomb affect the events in the novel?

The class structure such as Ewell's being below "normal" people in Maycomb and black people being even below them makes the events some what different, such as Atticus and Bob Ewell squaring up to eachover, Bob spits in his face and generally there would be a fight or violence taken but because Atticus is in a higher class and is a more polite, educated and a more well mannered person, he simply wipes it and walks of. So basically your answer would be, different characters react in different ways to events because they come from different backgrounds.. Maybe also the fact that they don't know and are and or are scared of the consequences.