Because those economies functioned in a relatively closed system of finance, and the actual cost of delivery was covered within that system. The actual cost of

Because those economies functioned in a relatively closed system of finance, and the actual cost of delivery was covered within that system. The actual cost of delivery is reflected in the price of getting the delivery. Or, if no delivery was easily available, it was because the cost of keeping such a system up, running, and easily available was higher than could be managed profitably. Doordash works today because venture capitalists are throwing millions of dollars at it, and dramatically subsidizing the cost of the delivery. In other words, you can do that today because someone else is willing to pay. The VC's money won't last forever though. The question is if the economies of scale it creates will be enough to reduce the cost of delivery such that it is a sustainable business. Most available data says "Probably not."