Yeah, I was going to comment the same thing. There should be little difference between the taste from LDPE lining in paper cartons vs. HDPE plastic containers.
FWIW, I do have a preference, I think milk is best drunk straight from a paper carton (in single servings, milk from the plastic "milk chugs" has always tasted worse to me).
Over here (NL), most milk is only on shelves for a day, they cart in new batches daily. We err, go through a lot of milk.