Humans also don’t store fat in their livers in the way and to the extent that migratory birds do. These animals are supposed to go through a cycle of bulking up their liver to a level that would be dangerous in other critters, then burning off all that stored energy on thousand mile migrations.
Basically what we do with foie gras is push this process to an extreme. Then eat the birds before they can work off the extra weight. But importantly if you push the process too far. To the point where it really does harm to the duck and cause problems. It vastly lowers the quality of the end product, making it less profitable.
Most of the horror stories you hear about foie gras come out of factory farms in Europe, Israel and Canada. These places produce cheap, low grade commodity foie for the packaged goods industry. You can pick up low cost tins of pate de foie gra or confit in gas stations in France. And the highest consumption of foie gras globally is in Hungary where some of the worst farms are. A Hungarian friend described picking up prepared foie as a cheap treat when she was a broke college student.
