Canada simply does not have the resources or infrastructure to deal with the fires.
I've heard that something like 90% of the Canadian population lives within about 90 miles of the US boarder. As you mention, there is not a lot of infrastructure north of that. I've taken many a fly in fishing trip to NW Ontario. There are logging roads that go well north. The problem is the dirt roads only service logging areas and Indian reservations. There is no way to setup a fire line when the fires start burning out of control in those remote areas..