Supposedly there is good data to suggest that people who work 10% longer make 40% more money. Now, that's not necessarily causal or anything, but it doesn't have to be. From a hiring perspective, it just has to be true. Unless you suspect that a candidate has scammed his previous employers, it is rational to prefer candidates who, based on their hours worked, are more likely to be effective at making money. Making money is generally the business of business.

"The U.S. Bureau of Labor Statistics reports that the average person working 45 hours per week earns 44% more pay—that is, 44% more pay for 13% more work"