As is so often the case, your "is just" papers over a lot of detail. When a firm sells a good for less than the bid price of the buyer, the marginal value captu

As is so often the case, your "is just" papers over a lot of detail. When a firm sells a good for less than the bid price of the buyer, the marginal value captured by that bidder is called consumer surplus. Firms do this for many reasons: they don't want the reputational hit of running an auction, they don't consider it worth the effort, they don't anticipate a need until after the revealed demand of the market is shown, and by that time it's too late to build an apparatus. Probably others I'm not thinking of. Scalpers capture this marginal value and in exchange provide the "service" of reallocating some of the goods to the buyers with the highest bid prices. (I put scare quotes around service here because I'm sure many consider it a pessimization.) If you're a wealthy person, scalpers may actually be good for you, because you don't have to compete with poorer people who have more time to refresh a webpage. You can just buy the good on eBay. On the other hand, it seems totally valid for the government to decide that it is in the best interests of the people that the consumer surplus in the system devolve to actual consumers.