I agree that the diversity is higher in the median, but disagree that the quality is higher. I live in the UK, but have spent time in the US, and for day to day shopping in the 3 cities I've spent lots of time in (SF, LA and Raleigh NC) the quality at the highest end is good but everything else is a crapshoot. Even at that most of the actual high end ingredients are European ingredients (cheese and butter, cured meats, olives) and cost 4-5x what they do in Europe. Not only that, I don't actually trust when I'm buying DOP parmesan from a us grocery store, but I know what I'm buying here.

The quality of supermarket meat in your average Tesco, or Asda ranges from acceptable to good. The quality in a Target or Walmart ranges from very very poor to good in my experience. As a textbook example the fabled wooded chicken breast is for the most part not a problem here, but was something I experienced on more than one occasion during my last month long trip to SF.