Bait and switch
is a venerable
marketing tactic that offers one item in the advertising, but when you arrive at the store, it isn't there.
The more sophisticated merchants actually have some few of the advertised items, but not nearly enough to satisfy all of the customers.
Also a standard ruse on the part of those in power to point out that any measures bringing in a more equitably regime, would only create in misery.
As in conservatives arguing with progressives, or even liberals, who raise the irrelevant spectre of communism.