They can’t cheat you on biandang because they control how much food they give you.
By the way do those places really import their own food, or do they go through an importer? I don’t see them speaking enough English to import shit and importing food is a complicated affair especially with the over the top fines you get for importing meat illegally. I don’t see a single restaurant consuming enough to warrant their own import permit. I see foods delivered by blue trucks though.