Milk with a multi-month shelf live can't be fresh, I believe. The fresh (mildly processed) milk I know turns bad within about a week, the "extended shelf life" stuff that was introduced a couple of years ago (in Germany) lasts for a few weeks. There is also "H Milch" which tastes very differend and can be stored at room temperature for several months.
Well, it can be fresh if you buy it soon after production, obviously. I assume the cow-to-cereal bowl pipeline is just a lot shorter for the cardboard cartons for whatever reason. Makes no sense, but the date discrepancy has existed for years.
