They have long-life milk because it keeps better in the heat - and there are still a lot of rural French houses where milk is kept under a cold cloth rather than in a fridge.
Can't agree about the chickens, though - we've found them to taste better than they do here - even the supermarket cheapy smaller jobs! We had the most delicious chicken I've ever eaten in a LeClerc supermarket cafteria one year, too. A lot of supermarkets offer the same 'range' of chickens you get here - bog-standard, free-range, corn-fed, and sometimes really expensive ones like Poulet de Bresse - but we just buy the cheapest ones and have always thought them lovely. Perhaps you may have been buying the ones which are only suitable for long slow cooking in a pot, which most supermarkets sell - I can't remember what they're labelled, though, sorry!
Most people can take a few jars of curry sauce, spice mixes, and so on - and run up a 'World Cuisine' meal if they want (we do - I take all my hot spices and you can buy fresh coriander generally) - and then stick to buying the things the French do best.