Why is only one of the reverse light on?

Why is only one of the reverse light on?

The purpose of the reverse light is to alert the vehicles in the rear
As well as the situation of lighting up the rear road for the driver when reversing at night, it can be seen that the reversing lamp plays a very important role. But why are some cars equipped with only one reversing light?
(because when reversing at night, you can't see anything in the dark behind the car, so the reversing lights are more important now.)
Most people have the impression that there should be one reversing light on the left and one on the right, but now more and more models are only equipped with one reversing light.
The car with a single reversing light looks like it's on the opposite side. It will feel strange. People who don't know think one of the reversing lights is broken?
From the perspective of production cost, symmetrical lights will make drivers paralyzed, and single lights can attract drivers' attention. For example, in foggy days, two symmetrical fog lights will make the rear driver mistakenly think that it is the brake light of the car in front, while one fog light can make the rear driver distinguish clearly. Two symmetrical reversing lights may make the driver mistake the car in front of him for retrograde at night, while a single reversing light is easier to recognize.