I don't know, but something I read a few months ago (can't remember where) and one of the comments on the linked article suggested that it is because of the way

I don't know, but something I read a few months ago (can't remember where) and one of the comments on the linked article suggested that it is because of the way cell phone fees are structured in Canada; Amazon can't afford to download books without charging extra, and isn't interested in the hassle of changing its system for a minor market. I have no idea if this is true, but it fits what little I know.