How many have even tried it? Companies are profit-seeking but that doesn't mean they will automatically make correct profitable decisions at every juncture. They're led by humans who generally make small conservative changes based on intuition. We see companies languish, stagnate, and miss critical strategic opportunities all the time.
Poor management is endemic. Managers are for the most part trying to maximize their ego/status. This means having their "underlings" grinding away (preferably in view) for as many hours as possible. That this situation is bad for the company doesn't matter since management is the one executing the poor decisions.
I think there is a change of attitude with a shorter work week. If I am working 9-5 at the same place everyday, I basically live there. It is easier to decide to take more breaks because there is no Friday to relax or get chores done or go to appointments. I take every other Friday off and it helps me focus more at work. I schedule all my weekday appointments for Friday (as much as I can). Monday thru Thursday I can push a little harder and be a little more focused because I know I have Friday (or a week from Friday) to take my dog to the vet, me to the doctor, or whatever else I need to do. I would love a real 4 day work week.
