Ask HN: Why can't autonomous vehicles solely rely on visible light sensors?

For example, you can bounce it off the ground under the car in front of you to "see" and measure how fast the car in front of that car is moving. That can be used to anticipate collision risks that even the car in front of you hasn't seen yet (and you cannot see with your own eyes).

Yes, mainly because CV just isn't there yet. Also because Lidar is better suited for the task than a camera+sufficient CV would be. The cost of Lidar is almost inconsequential anyways when compared with the total amount of building, developing, and testing an autonomous vehicle.

You are not always in an area where visible light is sufficient, additionally light sensors are prone to noise related error. If all of your sensors are subject to the same errors they may collaborate on mistakes

(In before Kalman filter)