In "To Kill a Mockingbird," why does Aunt Alexandra represent for Scout "the starched walls of a pink cotton penitentiary"

Aunt Alexandra is a person who lives on 'doing the right thing, following the rules, and acting like fine people act.  "She is a conservative woman concerned with social and class distinctions and bound to the traditions of the South. She tries to counteract her brother's liberal influence on his children by reminding them of their family's eminence and by trying to make Scout behave in a more ladylike manner." She wants Scout to behave like the sweet little girl.  To Scout this is like being in prison.  Her Aunt wants her to dress, act, and behave like a nice little girl.  Aunt Alexandra is unbending, like starched walls.  She won't budge away from her values or standards and she wants Scout to be the same way she is.  To Scout this is like living in a nice, pretty prison.