Well, all it really shows is that the "market" in this instance is incredibly inefficient. People need jobs, and if the vast majority of companies have a poor interview process, and 1% have a good one, assuming that this is the only thing that people care about (it's not), all that's going to happen is the 1% get the employees they want, and the other 99% still get some employees.

The market is likely inefficient for the same reason that the advertising industry is inefficient - difficulty to show than any given change independently improves outcomes.