Lots of people manage to drive in poor visibility without radar, lidar, etc. If that's safe and normal for people, the principle that self driving should work with just cameras isn't such a strange one.

I wouldn't call things like radar and lidar unnecessary but in principle a good AI vision system should be able to operate at the same level as a human eventually. Of course if you don't have such an AI just yet, you need a stop gap solution. But I wouldn't bet against AI getting there eventually. Probably not on Mr. Musk's accelerated and optimistic schedule though. But give it another five to ten years and things might look a bit differently.

What Waymo is doing now with much less than perfect AI is of course completely pragmatic and very impressive. I'm kind of eager to see them start operating self driving outside a few restricted zones in the US and for example in European cities. I live in Berlin, so probably we'll have to wait quite a bit for people to finally let go of their fax machines though apparently there are some trials with self driving buses about to kick off here now.