In Flannery O'Connor's "Revelation," why do only three of the characters have names?

A major theme of "Revelation" is Mrs. Turpin's misguided view of the world. She views everyone as part of a hierarchy, and from her perspective, nearly everyone is lower than herself and her husband. By referring to everyone else by labels that she's assigned them, rather than by their names, she strips them of their identity and agency. In Mrs. Turpin's mind, there's no need to learn the "white-trash woman's" name because she's "white-trash" and not worthy.

The climax of this story, though, is the vision that Mrs. Turpin has of people like herself and Claud bringing up the rear of the procession -- walking behind the very people she's deemed and treated as nameless and unworthy.

It's also important to note that Mrs. Turpin only thinks of Claud by name; it's the nurse who gives Miss Finley's name.