Market failure? Not necessarily. Usually a queue reflects a price that is set too low, so that demand exceeds supply, so some customers have to wait to buy the product. But a queue may also be the result of deliberate rationing by a producer, perhaps to attract attention – by a restaurant that wants to appear popular, say. Customers may regard a queue, such as a waiting list for health treatment, as a fairer way to distribute the product than using the price mechanism.