Walmart follows 'classical management' of negative reinforcement and cutting expenses down to the bone including salaries, benefits, and other stuff. They are willing to pay executives millions while letting most employees work for slave wages with little to no benefits to cut down on costs as much as possible.
Costco follows 'participatory management' in which management gets involved with the employees and empowers them to make their own decisions. Executives are not paid millions and their salaries are based on how well the company does to encourage growth. Employees are paid more so they will be more productive and with good benefits to take care of health problems and family problems so they don't interfere with work. If the company is losing money, they do job cost analysis to see what products and services cost more to support than the revenue they bring in, and then quality is improved on those services and products and if it cannot then those products and services get cut instead of the people and new products and services replace them.
Steve Jobs did this with Apple, cut out products and services that didn't bring in enough revenue to justify keeping them, cut his own salary as the iCEO, improved the quality of products and services or come up with new ones to replace them. Walmart and other 'classic management' companies just don't understand how to do that so they take it out on the employees instead.