I just happened to check the use by date on some milk this morning - use by 19 June - however I also noted the finer print on the side regarding storage:

Keep refrigerated and use within 3 days of opening. NOT SUITABLE FOR HOME FREEZING.

Once opened I am often using it up to 5 days later unless there is an obvious reason not to. With regard to freezing, in NZ, in the far North you used to be able to buy milk in plastic bags that you put in the freezer, then placed in a plastic jug, snip the corner off the bag and use when thawed. Am sure the cows down under don't have a recipe for producing milk with different keeping properties so it leaves me to wonder whether this is more about having you waste and therefore buy more and/or covering poor storage habits between the time it leaves the factory and arrives in the supermarket refrigerator. How often have you purchased milk that isn't as chilled as it should be and certainly has an extremely short life even in the fridge irrespective of the use by date? - More an issue in the summer though.

I imagine there's some stupid European directive about it somewhere. But yes, I imagine milk manufacurers make the most of it to get you to buy more milk.

The thing with the print on products that says "Consume within X days/months of purchase" cracks me up.

For instance, we bought a ton of Cava for the reception at my wedding. On the bottles it said "Consume within a year of purchase". Now as it isn't chilled in store, how do I know how long it's been on the shelf before I purchased it? As surely, I'd need to deduct this length of time from a year to get the true Best Before date. LOL

Do we have a different pasturisation process to NZ?

I have no idea.