Comment by vintermann

Maybe it's obvious, but you left out subsidized. US dairy production is extremely subsidized compared to Canada's. It's not in any sense "free trade". The subsidies would allow the US dairy industry to destroy Canada's (it might even without the subsidies, but the subsidies guarantee it). Once the local industry was destroyed, the US producers/government would be free to increase the price. No country wants that, which is why things like staple foods are subsidized and tariff-protected anywhere in the world where not doing so would give a large neighbor/bloc leverage over them.