The serious eats article covers it pretty well. There are two companies that provide foie gras for US consumption: Hudson Valley and Roguie. Both of which are distinctly not factory farming conditions. In fact, they are open to visitors and welcome outside scrutiny to prove that they are running a humane farm. The ducks have a lot more room to roam than in a typical farm, they're kept cage free, they're unstressed and happy, workers who have low duck mortality rates are given bonuses, and they're fed by hand. The ducks are not ill, they tolerate the feeding without complaint, they're healthy, clean, and completely unfazed by the process.
In short, the process of making foie gras in the US is pretty much the best
life a duck destined for slaughter can have. It makes for an easy target because it affects a small number of people, it's rare, it's expensive, and it's got strong associations with gluttony and indulgence. However, the briefest of inquiries into the life of a factory farm chicken or duck would lead you to the conclusion that eating chicken mcnuggets or KFC is a far more heinous crime. When is California going to ban farming practices that requires birds be debeaked because they're crammed into dirty, disease ridden hovels where they're so miserable that they will literally peck themselves to death? http://www.villagevoice.com/2009-02-18/news/is-foie-gras-torture/