Folks at that diner, and in that town, were literally for real saying racist things. That’s not an interpretation.
Really? Were you there, in the diner, at the time? I’m guessing NOT, or else you would’ve said “my friend Abby, who was seated next to me,” and not “the Original Poster.”
From my reading, it seems that folks in the diner were saying rather ambiguous things that could be taken in more than one way, and the author applied her own interpretation to the quoted dialogue. I don’t see how it’s intrinsically racist, for example, to point out that Chicago has some crime-plagued neighborhoods. Of course, this COULD be said in a racist way; it would depend on the surrounding context.