yep, I'm from Canada, and I can keep snakes form anywhere in the world except my own back yard. Non native wild life doesn't pose as much of a threat to us, our harsh winters will take out any runaways. The laws are to protect our native wildlife from the pet trade, so you don't have a bunch of yahoos scooping up garters and selling them to the pet stores. Indigo snakes are a good example, their wiki entry says this: "As a result of overzealous collection and the destruction of its habitat, it is an endangered species", and I'm sure that could happen to any snake here (indigos just happen to be docile and pretty).
Mind you, we do have some non-native problems. Red ear sliders, for example, are fairly aggressive and tend to over power our native turtles. But nothing on the scale of what you guys have gone through with non-native animal problems. I have corn snakes from the US and they wouldn't stand a chance in the relatively mild winters Vancouver has, let alone my spotted python.
