Scout's questioning of why Boo Radley has never run away from home suggests that Scout's attitude toward Boo has shifted from one of fear to one of genuine empathy. This arises after Scout learns that Dill has run away from home because of his stepfather. Dill acknowledges that his folks aren't mean and that they buy him whatever he wants; the catch of this is that they neglect him and do not express their love or interest in him.
The difference between Dill and Boo, however, is that Dill has the capacity to run away and a place to go to; Boo, on the other hand, is trapped by his circumstances and has no other family members or friends to run to due to the lifelong nature of his isolation. It thus becomes clear to Scout that Boo has lived a difficult life and that he deserves her interest and sympathy.
In Chapter 14 of "To Kill a Mockingbird," Dill arrives after having run away from home because he now has a stepfather. When Scout asks him why he has run away, he tells her that "they [his parents] just wasn't interested in me." Either they are gone or when they are home, they sequester themselves in a room by themselves, Dill tells Scout. To make Dill feel better, Scout tells Dill that she was about ready to run off herself. Besides, she says,
You don't want 'em around you all the time, ....Dill, you couldn't do anything if they were.
Pondering his words as well as what has occurred with Dill in his home, along with his wish to "get a baby," which the maturing mind of Scout deduces that Dill lacks real love despite the gifts his parents bestow upon Dill. Realizing the similarities in Boo Radley's home where there is no love, either, and neglect of Boo's needs as well, Scout gives voice to her thoughts: "Why do you reckon Boo Radley's never run off?" She questions why Boo would not do as Dill as done since their situations are somewhat similar. But, Dill responds that perhaps Boo has nowhere to go.