I work in a restaurant and, like the restaurant mentioned above, we can only take orders for the lunch menu and happy hour menu during specified hours. Even though the hours are clearly shown on the menus, everyday customers ask if we can bend the rules for them so they can save a buck or two. Unfortunately, my boss won’t have it, and we get into trouble if we take an order for one of those menus too early or too late.

This applies to the place I work, of course, and may not be the same issue at the restaurant you commented on. Just trying to shed some light on the situation! :)