The spectacle of corporate magnates from Detroit pleading to be on Uncle Sam's dole is a sordid one. So why aren't more Americans appalled? One reason is widespread misunderstanding -- much of it sowed by these auto makers -- about the size of their firms. The Big Three, we are told, are "too big to be allowed to fail."

This myth begins with the idea that GM, Ford and Chrysler are so huge that if they go belly-up, the livelihoods of a disproportionately large number of workers and suppliers would be affected. At once, the...