[timbit42]

While milk bags are not as environmentally friendly as glass, glass is very heavy and expensive to transport and requires a fair bit of energy to wash and sterilize for reuse.

Compared to cardboard cartons (which are lined with plastic to make it waterproof) and plastic jugs, milk bags are more environmentally friendly even if you put the bags in a landfill and recycle or reuse the cartons and/or jugs.

That said, even if milk bags are not recycled, you can reuse them. Many Canadians cut one of the short ends and rinse them out to make a freezer bag or a lunch bag which can be reused multiple times. Some people use them to hold nails or screws.

Source: https://theconversation.com/milk-jugs-cartons-or-plastic-bag...