HTA OREG 611 SAFETY STANDARDS
(6) The condition and security of each prescribed mirror shall be inspected and,
(a) no prescribed mirror shall be missing;
(b) each mirror shall be securely mounted and maintain a set adjustment;
(c) no mirror shall be cracked, broken or have any significant reduction in reflecting surface owing to deterioration of the silvering; and
(d) in the case of a motor vehicle where there is no rear window, or the view through the rear window is restricted in such a way as not to afford a driver a clear view to the rear of the motor vehicle, the outside rear view mirror or mirrors shall not be missing
Motor Vehicle Safety Act.
Prescribed Mirrors Section 111
(11) An outside rearview mirror shall be installed on the drivers side of every passenger car and three-wheeled vehicle.
So yes, you do need the drivers side mirror and failing to have a mirror puts your vehicle in a position of not meeting safety requirements, which could be an "unsafe vehicle" offence, plate removal and towing of vehicle.
One of the cars I owned in college did not have a passenger side mirror, not illegal, but I just went to a scrap yard and bought a matching mirror for $50....1/4 of the cost of a new one from the dealership
Above is merely a suggestion/thought and in no way constitutes legal advice or views of my employer. www.OHTA.ca