I wonder if thats because most of the Canadian population is localized to their mega cities like Toronto, Vancuver etc while US has a much larger rural population.
Vancouver is famous all over the world as an attractive city (for example I live in Berlin, Germany, and many people I know would like to visit Vancouver). I've never been there, but I have heard it is next to the sea AND next to the mountains, and it lies in a first world country with a solid economy and good health care. Maybe the prices just reflect demand?