Canada doesn't have a lower rate for postcards like the US has. The logic is that they don't cost less to process than normal envelopes.
If it makes you feel better, our parcel rates are often better. I just sent a couple of massive boxes to Australia. Canada Post charged me $201 Canadian by surface. The US postal service had two options: bag service, for $260 US, or regular surface parcel surface (like Canada Post used to ship them), for $310 US.