Why Can’t You Buy Chicken Hearts in the U.S.?

Walking around the Adelaide Central Market, I’m struck by the variety of meat available. Of course there is pork, beef and chicken. There is also rabbit, goat, boar, and buffalo. There are also chicken hearts, giblets, and liver. In abundance and of great quality. So, here’s my question: why can’t you find that in the U.S.? There was a time when you could. What happened? What do you think, meat-eating reader? Would you consider buying rabbit or goat if it was readily available? What about chicken hearts?