Allan
In Ontario, milk used to be sold in large white polyethylene jugs that were refilled.
Several off-taste issues arose as a result of previous users having used the jug for storing kerosene, gasoline, and solvents of different types.
Polyethylene is actually porous to volatile organic compounds and despite vigorous washing, the taste remained.
Some real poisoning incidents also gave reusable plastic jugs a bad name. In one case, a small boy found some milk left in a jug in the barn on his parents’ farm. He was thirsty and drank the milk.
The ‘milk’ was a white-coloured concentrated organophosphate pesticide that was an anticholinesterase inhibitor. His entire nervous system was disabled. he went into a coma, and died some hours later.
In Canada (not BC, however) 1.33-litre bags, sold in packages of 3 (4L, or approximately 1 gallon for US readers), have been an unqualified success.
“Leakers” are almost unknown once the product has left the processing dairy, and the plastic 1-litre jugs are cheap and available everywhere.
But as to WHY some jurisdictions endorse bags and others not, the answer is probably lost in marketing, preferences, economics, and personal experiences.