Somebody's disposal is making a noise they can't describe, so they tell ChatGPT exactly that, in a paragraph, with the sound and the model and how long it's been happening.
ChatGPT doesn't look for whoever ranks first for plumber near me. It reads local plumbers' websites and their reviews, hunting for one that has said something about that specific noise. If you've written about it, you get named. If you haven't, somebody else does.