The Derb says:

There are many ways to ration a service. You can ration it by expense, excluding those who can't afford it. You can ration it by fiat, excluding applicants according to some set of rules administered by gatekeepers. Or you can ration it by complexity, paving the access path to it with tests of intelligence, patience, and persistence, thereby excluding applicants who are less well-equipped with those attributes.

The latter method has become the preferred ratoining method of the American republic, probably for the reason that great numbers of people feel that intelligence, patience, and persistence are infinitely malleable.