Because that region of Canada now does not have an EFFICIENT and SAFE way to move their raw product to refineries. That boils down to a tightening supply amidst ever increasing demand-- so Prices Go Up.
LOL... It's about M O N E Y stupid--- it was never about "saving" anything. If North American oil just got more expensive-- then foreign oil companies MAKE MORE MONEY. Burisma and China are happy little f**kers right now. Wake up!!