Ed Prescott has argued that differences in working time between Europe and America are explained by differences in tax rates, not underlying cultural differences. In his Wall Street Journal piece, Prescott explains:

According to the OECD, from 1970-74 France's labor supply exceeded that of the U.S. Also, a review of other industrialized countries shows that their labor supplies either exceeded or were comparable to the U.S. during this period. Jump ahead two decades and you will find that France's labor supply dropped significantly (as did others), and that some countries improved and stayed in line with the U.S. Controlling for other factors, what stands out in these cross-country comparisons is that when European countries and U.S. tax rates are comparable, labor supplies are comparable.

This is a fascinating result, and conforms nicely to my belief (as distinct from ability to demonstrate conclusively) that everything, and I mean everything, can be explained by differences in relative prices. Don Boudreaux at Cafe Hayek sums it up this way.

So, the much-ballyhooed cultural differences allegedly separating Americans (or Anglo-Americans) from continental Europeans don’t really explain the observed differences in work patterns across these countries. In fact, the reason Americans work so much more in the market than do Europeans is that Americans’ taxes are lower at the margin.