Acting like a lady

Scout had difficulty "acting like a lady." Aunt Alexandria was very concerned about this. Girls growing up in the South in the 1930s were expected to act in a certain way. They dressed in a certain way. How does this compare to the way in which Mayella Ewell appeared to be raised? When Atticus questioned Miss Mayella and referred to her as "Ma'am", she took offense to his courtesy. Was Mayella not a girl growing up in the South in the 1930s as well? Is the difference between Scout's situation and Mayella's situation due to education, affluence, the difference in their respective fathers, or something else?