I didn't realize people still used bagged milk.  As a child we lived back east and used bagged milk, but then moved to Canada's  North and then West and never saw them again.  I didn't realize Ontario and other places still used them, but they certainly don't use them in western Canada anymore.  Even if one could find a bag of milk, the containers used to hold them aren't sold in BC, so people would have to find another container (like the plastic 4L ones) to pour them into - what a pain it would be.  Pretty sure bagged milk is like the "Canadian" Eh.  An Ontario or eastern thing.  There isn't much that is  "uniquely Canadian" that all Canadians instantly identify with anymore.  If they/we do, it's likely in the US too, making it ununique.