The American economy has become a kind of piñata - lots of treats in there, but no guarantee that you will get any, making people prone to frenzy. It was a tragedy, yet it did not feel like an accident. All those people were lined up in the cold and darkness, because of marketing forces that have produced this day called Black Friday. They were engaging in early-morning shopping as contact sport. American business has long excelled at creating a sense of shortage amid abundance, an anxiety that one must act now or miss out.