In such a safety-critical system, it's important to have backups. You need at least two cameras to accurately estimate depth, and cameras can fail for a variety of reasons (sun glare, low lighting, heavy fog). Radar, at the very least, is a backup for the cameras. Also, with vision, the best you can do is estimate distance, whereas with radar and LIDAR you are explicitly measuring it.
>Also, with vision, the best you can do is estimate distance, whereas with radar and LIDAR you are explicitly measuring it.
But is there any evidence you need to measure distances? We humans can navigate the world without walking into walls, so long as we're looking where we're going. For a machine to navigate the world it should be possible to do it via vision. And Tesla's do have multiple cameras to be able to measure depth.
And radar is not a backup for cameras. The resolution of the data is terrible and you can not rely on it to do any sort of driving except braking if it thinks there's an obstacle. Radar is also susceptible to problems as well, which is why Tesla's and other cars with radar can often go crazy thinking you're gonna crash randomly.
