Just a heads up, Carrefour actually is a very large multinational hypermarket chain, not a local grocery. It's one of the top ten retailers, on roughly the same scale as Walmart and Costco. They just don't have a presence in North America.
Mind you, the food they sell is still significantly better than an equivalent low cost grocery in the US.
I find it really odd that when comparing European and American grocery stores people somehow turn a blind eye to the "supermercat" places you can find about three to a block here, whose sole mission is to sell dusty canned goods and 90 degree wine to desperate people who can't find anything better.
Mind you, the food they sell is still significantly better than an equivalent low cost grocery in the US.