Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Omniscient)
The characters in Maggie are in a bad way, and our narrator doesn't really seem to care. Like, life is clearly super rough for them, but so it goes—it's not the narrator's problem. This attitude is a classic naturalist narrator quality: They're just there to give us the facts. Plus, since our narrator isn't part of the story, these harsh conditions don't directly affect him or her. The narrator can report on them from a safe distance, just calling 'em like he or she sees 'em.
That said, in order to paint as full a picture as possible—which is the aim of a naturalist narrator, for sure—the narrator is able to hop around among the characters, offering insights into each as it suits the story. In doing so, we get an up-close-and-personal picture of just how hopeless life is for this cast.