Every dodo is a bird - the concept of a bird is useful to explain what a dodo is (in part, at least). In this case, I happened to use manufacturing inputs for

Every dodo is a bird - the concept of a bird is useful to explain what a dodo is (in part, at least). In this case, I happened to use manufacturing inputs for a specific reason: cars are the inputs to the end product of car rental companies. In the same way it makes sense to pay for product inputs after you've sold an iphone, it makes sense to pay for the cost of a car after you've made the money renting it. If you have to bootstrap, you can't leverage economies of scale nearly as effectively.