No, they come in cartons and plastic jugs, at least at the superstore.
Milk carton
milk cartons can be put into paper or plastic. Either one is fine.
They should all be recycled, as they can all be remade into the original items.
Milk stays fresh longer in cartons, over see-through containers which means it tastes better, for longer... Cartons are also more eco-friendly as opposed to plastic jugs. The down side is cartons are more expensive.
if you are referring to Polyethylene; polyethylene is one of the world's most widely used plastics in the world and can be found in plastic bags, plastic milk cartons and other packaging
hdpe
They don't, and there's no reason to be so stereotypical. Milk is sold to consumers in cartons just like in the States, not bags.
No. The cardboard in milk cartons contain plastic, and your disposal won't enjoy the cardboard.
They used to sell milk in plastic bags
yes
There is no specific collective noun for cartons of milk, in which case, a noun suitable for the context of the sentence is used, for example a shelf of cartons of milk, a row of cartons of milk, etc.