When I was living with my parents (family of 4), we used my trailer to go to the grocery store, 2 km away. I have the old model of Bikes At Work, the 48".
Now I live in Montréal, and I have more places to get fresh food than I can count on. I have 3 butchers, a bakery (hmm, fresh bread!), a cheese and nuts shop and a full-fledged grocery store within 800m. I am also at walking distance of what they call the largest outdoors market in north-america (no idea if it's true, but it's huge) where I can find whatever vegetable and fruit imaginable. And around that market are more specialty shops, fishery, butchers, bakeries, vegetable shops, etc. Kind of a dream for a food lover like me.
I do my groceries by foot with my flatmate using the massive bags they sell at Costco (where he works). I also go there by bike sometimes, on the way back from work, when I want to do something special.