Where it really falls apart is that a restaurant has a predefined menu and no items are allowed to have unknown complexity (someone asking items out of menu jus

Where it really falls apart is that a restaurant has a predefined menu and no items are allowed to have unknown complexity (someone asking items out of menu just gets a “no”). Estimates are based on actual measures, not guesses. There will be accidents, but those will be rare enough to not have to be planned for. In that respect, a restaurant queue is a lot more akin to a factory, and is fundamentally different in nature.