When backing an articulated vehicle, why is backing toward the driver's side (left) preferred over the passenger's side (right)?

1. The tractor's exhaust pipe is located on the right side
2. The driver has a direct view of the trailer's path out of the side window and in the side mirror, minimizing blind spots
3. The trailer air lines are shorter on the left side of the vehicle
4. Traffic regulations in the Philippines prohibit backing to the right