Canada is now the largest foreign supplier of oil to the US, to the tune of some two million barrels of oil a day. Should we be? Shouldn't the Canadian government be trying to keep that oil here in order to satisfy our own energy needs? A non-economist might be inclined to respond in the affirmative: the prospect of running out of fuel seems the sort of thing that a government should be trying to prevent - especially in a country as cold as ours!
But that's not how an economist would look at the problem.