Except, like I said, I use only organic dairy and it lasted well past the sell date at home.
Sorry, I was in the process of writing my reply when you posted and only skimmed over the replies before hitting send

. I've always assumed that it was due to extra preservatives, but that's just a guess on my part - maybe it's not the case after all.
What I've mainly noticed is that a lot of UK dairy products (such as cream cheese, brie and other soft cheese), jars of sauce etc. say 'consume within 3 days of opening' on the packaging, whereas I don't remember seeing this written on similar US products (which was the reason for me asking my US roommate)... so I assumed there was something slightly different in the product ingredients if they could be kept in the fridge for longer than 3 days. With milk, I've always consumed it or thrown it away by the sell-by date so I couldn't say whether or not it lasted past that date in either the US or the UK.
I've noticed it with bread. It goes stale faster and moldy way faster in the UK. Weird. Anyone know why? Is it something to do with the climate here?
Again, I guessed that it was due to preservatives being added to US bread - in the US I found that supermarket bread (i.e. packaged on the shelves, not freshly baked) would last for 2-3 weeks before starting to go stale, but in the UK, it goes stale in maybe 3 or 4 days.