No operator of any motor vehicle shall discharge or pick-up a passenger other than from the extreme left hand or portion of any roadway. When it is practicable to do so, a vehicle discharging or picking up passengers shall do so only by turning off any lane of through traffic. No person shall leave or enter a motor vehicle which is upon a traffic lane of a public roadway other than from the left hand side of the vehicle unless the vehicle is completely pulled off the main roadway or as far left as practicable.