I guess the quality of the food you have in the US is very different to what we have in Europe (or we just have lots of preservatives). Fresh milk usually lasts a week (I usually get the smallest 250ml pack), where as I can have 1 litre of UHT milk last a month without any noticeable difference. Cheese... well it lasts until it's eaten, it just goes a bit hard. I've had a packet of grated parmesan in the fridge for nearly a month, and a wedge of pecorino uncovered for two months, and both are still good.