As of 2012, the pharmaceutical companies Abbott Laboratories, AstraZeneca, Aventis Pharmaceuticals, Bristol-Myers Squibb Company, Eli Lilly, GlaxoSmithKline, Janssen, Johnson & Johnson, Novartis, Ortho-McNeil, and Pfizer provide low-income, elderly people with a card guaranteeing them discounts on many prescription medicines. Why would these firms do that?