tiki: They probably get lower rates of delivered to private homes...the angle is to go the cheapest route.
Most shipping companies have lower rates for a commercial designation. Having a parcel delivered to your home generally costs more, not less.
Having the Literature delivered to a personal address rather than the Kingdom Hall will have another reason for it. I dunno...maybe the WTS plans on not being a "resident" corporation in Canada anymore. Maybe the WTS plans on eliminating the Canadian Branch Office.