In late 2008, a fast-food burger restaurant in Sweden received an odd complaint letter. It was from a mother of two, asking the chain to get rid of the boxes that its kids’ meals were packaged in. Her children only wanted the fries and toys, she said, and she was annoyed at having to throw the boxes straight into the recycling bin. It was an unusual request with an unusual outcome. Max Burgers — Sweden’s No. 1 burger chain — decided to do away with the kids’-meal boxes in all of its 75 restaurants, explaining to customers that it was reducing waste. No one complained. In fact, sales of kids’ meals rose. The company had turned sustainability into a selling point.