You have a good question. I've noticed that rice sellers like to ask if it's spicy, and even put some chili oil on it for me after I say I don't want chili, and then argue that the chili oil isn't spicy when I chastise them for it. It seemed to me that they wanted everyone to eat spicy food because the spicy flavor could cover up the lack of flavor in his food, which was too obvious when there was no spicy flavor. But since not everyone eats spicy, he had to ask. I don't know if you've noticed, but if you don't say if you want chili, he'll usually take the initiative to put it in for you.