What is the principle behind the low beams not turning off when the high beams are on?

[LaIan]

When the high beams are turned on, the car's low beams also remain lit, primarily controlled by the headlight controller, which can be cumbersome if frequently switched back and forth. Compared to low beams, high beams have a longer range and greater light intensity, but their use should be determined based on the road conditions the car is traveling on. Usage of high beams: 1. On roads without central barriers or center lines, high beams should not be used when meeting an oncoming vehicle within 150 meters. 2. High beams should not be used when meeting non-motorized vehicles on narrow bridges or roads without central barriers or center lines. 3. High beams should not be used when turning at intersections controlled by traffic signals. 4. In low-visibility conditions at night, such as when there is no street lighting, poor lighting, or encountering fog, rain, snow, or dust, high beams should not be used when a following vehicle is traveling close to the vehicle in front in the same direction. 5. When overtaking at night, high and low beams should be used alternately to alert the vehicle ahead. 6. High beams are not recommended in well-lit urban areas.