Earlier quoted context omitted.
That simply isn't the colloquial definition of a shortage. If rent is $20,000/month for a studio, going "well technically you can always get one if you can pay $20,000 a month so there's no shortage" is kind of a uselessly pedantic comment.
I agree, in the case of "rent is $20,000/month" calling that a "shortage" doesn't say anything. It is no different than a case where "rent is $200/month". There is nothing the reader/listener can learn by adding shortage into the mix in either case. Pointless, yes, but I'm not sure pedantic is the right term for describing using a word in a way that does not communicate anything. But, to each their own.
Your definition of shortage is too narrow. Price is always able to select a buyer. People will skip eating if you give them enough money. But if that only supplies a couple percent of buyers, that's not going to disprove a shortage.