Why is left turn allowed at red light?

[LaRowan]

Motor vehicle traffic signals and non-motor vehicle traffic signals indicate: When the green light is on, vehicles are permitted to pass, but turning vehicles must not hinder the passage of through vehicles and pedestrians; When the yellow light is on, vehicles that have already crossed the stop line may continue to pass. When the red light is on, vehicles are prohibited from passing. At intersections without non-motor vehicle traffic signals or pedestrian crossing signals, non-motor vehicles and pedestrians should follow the motor vehicle traffic signals. Additional information: Pedestrian crossings, overpasses, or underpasses should be installed at road intersections and sections with concentrated pedestrian crossings. In sections with frequent blind pedestrian traffic, audible signal devices should be installed for pedestrian crossing signals.