Not an absoulte requirement to have them in Canada. Much of Canada isn't that cold, west coast actually doesn't get much below the freezing point. Urban areas in Eastern Canada typically aren't cold enough that they are a neccessity (though they are likely nice to have). In fact, even in the Prairies or North where most block heaters are installed, it's only necessary on cars parked outside when it's -20C or colder overnight or the whole day (park in am, start again after work). If it's always garage parked, there's no need.
When I say necessity, they are needed to be able to start, with most cars, that point begins at around -20C (generally, better condition vehicles with synthetic should be able to tolerate lower and start fine). They are nice to have at any point below freezing, since you'll get cabin heat faster (particularly with diesels).