I wonder if this has something to do with it -- namely, they refuse to be turned into bazaar hawkers, thinking that it demeans their important job (which is, after all, primarily for our safey)? (Of course, a counterpoint would be the notorious US Airways credit-card pitches that FAs must hate.)

Also, I agree with other posters that duty free is generally simply less attractive to American consumers. But it can be useful in other countries. For example, just the other day I bought duty-free liquor heading into Turkey, and found the prices at the airport (either the departing airport or IST inbound duty-free) substantially lower than in Istanbul. I am assuming that this is because of taxes.

I am assuming that this is sarcastic. You can't possibly be so burdened by the duty-free requests that it influences your airline choice, especially when the difference is so great??