Proving Walmart CHOOSES to have too few managers for each of its stores. And does NOT pay them overtime (which is why they are salary, not hourly).

Having "too few" managers saves the company a ton. As the manager gets paid the same whether he works 40 hrs or 80 hrs, the company gets free labor, as well as saving on matching payments to a 401K account and reduced medical insurance costs because there are fewer people on the payroll.

The name of the game is payroll as a percent of sales. The more money you can beat out of your employees, the better the profits. A store manager in particular, if he isn't on the floor ringing up sales, is a cost to be minimized. Recruit him by dazzeling him with promises of a 6 figure income, without telling him he'll have to work like a galley slave to do the job.

Steve