It is no self evident fact that false negatives are less costly than false positives.

Understaffed projects might lead to failures, people quitting, expensive consultant aid etc.

Hireing a bad programmer and two good and ending up giving the poor one easy tasks or letting him go might be cheaper than hireing two good more slowly.

In general I feel the recruitement process is so random anyway that employers should just get it done and pick someone after throwing darts at a billboard with resumés for picking some to interview.