As much as I love Tesco, and I do, their selection of USA wine leaves something to be desired. I almost get the feeling that there is some sort of prejudice against American wines, especially Napa as there are a couple of Sonoma wines featured. It's not as if Argentina, Australia, and Chile, who are all well represented, are closer to Blighty than the United States and it's a shipping and logistics issue. Also, they are obviously not members of the European Union.
It cuts both ways I suppose: I have had Americans tell me that the English only drink cheap wine. After being initially insulted I have to admit that a visitor, from any wine producing region of the world, would pity the poor Englishman's taste buds after witnessing the choice of Californian wines available to him.