Our worker productivity isn't simply a measure of how hard we work. It's also dependant on how many hours we're willing to work in a given day. Our high worker productivity is largely due to the fact that we have a low marginal tax rate. Much of Western Europe had high productivity after WWII, back when they had lower tax rates. As taxes increased, however, worker productivity decreased. See Prescott's "Why do Americans Work so Much More than Europeans?" for the full explanation. Puritansim probably plays some minor part, but money is the primary incentive to work hard.