In To Kill a Mockingbird, there are many adult characters who Scout and Jem come in contact with. All of these adults have expectation about how Scout and Jem should act, and this even extends to Atticus as it becomes known that he will defend a black man in court. Maycomb, AL, though a fictional town, is modeled after the attitudes of people in the Deep South during the first half of the century. They seem stuck in their ways, and refuse to change--especially when it comes to race. They also seem hypocritical in their views; they feel sorry for the Jews in the concentration camps, but do not acknowledge their own prejudices towards African Americans.
For the most part, the adults stick to their own "code" of expectations. Aunt Alexandra disapproves of Atticus's choice to defend Tom Robinson, and disapproves of how he raises Scout and Jem (she wants Scout in particular to act more traditionally ladylike). Stephanie Crawford, a neighbor, has her expectations about race relations and is a well-known gossip. Scout's female teachers expect her to be ladylike, to not read at home, and to subscribe to their world views.
Miss Maudie, on the other hand, breaks the code. She does not gossip or concern herself with the hypocritical views of her neighbors. She keeps to herself, and treats the kids almost like adults. She is caring and motherly, but independent. Compared with the other female characters, she is trustworthy, outwardly unbiased, and rational in her expectations. To other characters, she can be seen as "breaking the code" or "acting improper" but she does not care.