Yes, there are millions of jobs at retail stores, restaurants, call centers, hotels, and day cares — but most of them are lousy and have been for decades. They offer low pay, few benefits, and no career paths. Conventional wisdom holds that bad jobs are the unavoidable price of low-cost service. They are not — and some companies are realizing that the way they run their operations, including treating their employees as replaceable commodities, is not sustainable. In the past three years large companies including Walmart, McDonald’s, GAP, and Aetna have raised wages. Walmart is investing more in training and is streamlining operations to help store workers be more productive. GAP is experimenting with more-predictable schedules. And Aetna is letting call center reps use more discretion to meet customer needs.