Why are all the street lights and ground lights on in California during the day? What is this for?

American car lights are on during the day. Because for safety reasons, American cars are designed to light up automatically when they are lit
Shops or decorative lights in commercial areas in the United States are also bright during the day. To look good.

Street lights in the United States are light-sensitive and automatically turn on and off.

In the homes of ordinary people in the United States, the yard lights are lit at night, so that pedestrians passing in front of their own doors will not fall down because they can't see the road.

In the United States, where construction is carried out, such as apartments, buildings, and building repairs, under the platform, it is light during the day and night to facilitate pedestrians to see the road surface.

Plus, electricity is cheap in the United States. If the United States because of lighting, pedestrian accidents, to pay a lot of money, compared to the electricity, much cheaper. Therefore, in many places, it is better to be bright during the day than to allow pedestrians to have accidents.