You can have a shortage for other reasons. In a perfectly liquid labor market (which only exists in theory), you can also have shortages. The canonical exampl

You can have a shortage for other reasons. In a perfectly liquid labor market (which only exists in theory), you can also have shortages. The canonical example is a price ceiling. If the government comes in and says that you can't pay more than x dollars for a thing, then some people willing to pay x dollars will not get the thing. That's a shortage because they wanted to pay the market price (in this case a government fixed price), but they couldn't obtain the good. In cases of shortages, methods of discrimination other than price must be used to decide who gets the goods, and who goes without. Without a price ceiling, the price would increase so that the quantity demanded becomes equal to the quantity supplied. Basically a bunch of people deciding they would rather something else because the good is too expensive.