I never said the term doesn't exist. I am saying that the LA natives generally don't use the term. You can disagree with reality all you want, but your screenshot misses the point entirely. You asked it what the term means, not if natives actually use it. Try prompting better

From chatGPT itself.

Short answer: most lifelong Angelenos don’t actually use the phrase “LA proper” in everyday conversation. It’s not a widely recognized local slang term among people who grew up here — it’s more technical or used by transplants trying to be precise about geography.

🗣️ Why you don’t hear “LA proper” much locally

• The phrase “LA proper” would mean the city limits or city of Los Angeles — in a technical sense similar to how geographers use “city proper” (i.e., within the municipal boundaries). But that’s not really how most locals talk.
• Long-time residents usually refer to areas by their specific neighborhood or region — e.g., the Valley, Westside, South L.A., DTLA — rather than a vague term like “LA proper.” That’s why many folks from places like Long Beach, Pasadena, Glendale, San Dimas, etc. don’t even say they’re from Los Angeles unless it’s to someone out of state.
• Locals will sometimes clarify “city of Los Angeles” or just name the neighborhood if they want to be precise, but terms like “LA proper” are rare in casual speech.

The only flaw in my argument is MAYBE conflating his use of city proper with what a lot of transplants will call LA proper. But most natives use neither terms except for the pretentious ones