[gambiting]

>>Seems to me like the real motivation is defending their own agricultural industry. American chicken is cheaper and likely just as good.

Well...if you stop and think about it for a second - of course it is. If our, European farmers have to abide by certain animal welfare standards and the American ones don't, then of course American meat will be cheaper. Equally, I wouldn't want to eat chicken meat from China or Vietnam - their animal standards are nowhere near ours, so why should they be sold here? If Americans improve their standards then they are welcome to our markets.