I believe that's true, with some exceptions (e.g. a one-way U-Haul rental, among others), but the question with Nexus would go beyond one-way or US rentals in Canada. For example, renting a car in Canada to spend the weekend in Vermont, returning the Canadian car to Canada. Of course that scenario is quite legal but not totally clear re:Nexus (and with contradictory responses here). That's how I read the original question, anyway.

=aw