I mean - when you ask StableDiffusion to draw a dog astronaut, everyone gets that the image it returns is made-up, right? Nobody expects the AI to return only "true" images of existing things - it was trained on fictional images as well as photographs, and people understand that it can imagine new things beyond what it's seen. Nobody expects SD to emit an error like "I can't draw a dog astronaut because they don't exist".
So why do people expect ChatGPT to work differently? Even with developers who presumably understand the technical details, I constantly see people acting as if it was an error mode for ChatGPT to say something that isn't factually true about the world. How is that any different from calling SD a liar because it drew a dog astronaut?