[goplusplus]

Comparing the price of milk and Canada versus the US isn't a 1:1 comparison. Canadians pay much less in taxes to support their dairy industry than Americans due to supply management in Canada (i.e. not producing more milk than needed, paying for that production through subsidies, and then wasting it). So, in-store higher dairy costs in Canada are closer to true production cost than in the states.

There are a lot of other factors here too, one being that during the 70-80s American agricultural legislation focused much more on large scale farm operations than Canada and as a result it is much harder for small farmers to get by in the US.

Regardless, even with all other factors being equal dairy costs would still be slightly higher in Canada since due to generally higher taxes and higher farm wages.