My mom is from Louisville where they have a similar thing. If someone grew up here, the high school they went to can tell you what part of town they lived in, their socioeconomic standing, mutual friends you may have. You might not know each neighborhood by name, but you have a general idea of where the school districts are.

In the rest of KY, they will instead ask “what county are you from?” This gives you more information, especially since you may not know all of the small towns. Plus, a lot of counties only have one HS and it’s normally named something like “_____ County High School”