Large retail chains have started requiring customers to wear masks inside all of their stores, as coronavirus cases surge across the country and politicians and public health experts clamor for widespread use of face coverings to stem the spread of the disease. After Walmart, America’s largest retailer, announced on July 15 that it would mandate in-store mask-wearing, a flurry of other companies, including Kroger, Target and Walgreens, followed suit. This means that customers will be required to wear face masks in stores even in places without local mask ordinances. The National Retail Federation has encouraged companies to set nationwide mask...