No, Canadian homes are not built to resist the cold. They have the same silly 3cm cardboard walls that American houses have. This was very stunning for me coming from a country where the temperature rarely drops below 0 degrees Celsius. I have learnt that the Canadians only feel like they are being eco-friendly because the only place they are comparing themselves with is the US. I mean: a remote control for your car's motor so you can have it pre-heat, half of the people driving around in pick up trucks or the toilets having about a million litres of water in them.
Effective R value and the air barrier are a lot more important than thickness or material (of course material choice factors into R value, but better materials generally hit higher R values at lesser thickness...).
Modern building codes require a vaguely reasonable R value.
