Another item to consider is how large the risk of relapse resulting in a bad outcome is relative to other risks involved. The FAA medical requirements may not actually do a particularly good job of preventing bad outcomes. Consider the cases we have all heard of where pilots have a 1st class medical and then unexpectedly have a heart attack on the flight deck. It is rare, but so is relapsing while on all the monitoring. There is likely no way to completely eliminate all risk of alcoholism or some other medical problem incapacitating a pilot or causing an error and bad outcome.
I do not know if Canada is laxer or more stringent. I suppose one could try and research the rates of these problems to get a sense of it.
