So have undeveloped land prices risen as much as existing houses? It seems like the obvious solution is to add new housing outside of town to serve the unmet demand, as every metro area in the US has done for over a century. With so much land and so few people, why hasn't Canada done this too?
Because most of Canada is uninhabitable. It's like asking why the entire state of Alaska has fewer people than live in Seattle if it has so much land. And not "metro Seattle", just... Seattle.