And it's quite obvious that there are at least some situations in which vision will not work whatsoever - e.g. dense fog. I personally would quite like my autonomous vehicle to operate happily through dense fog. If you're happy to pull over to the side of the road and wait it out, be my guest.

Having multiple orthogonal subsets of the electromagnetic spectrum at your disposal provides redundancy and diversity - two features that simply CANNOT be accommodated with a single class of sensor, not matter how advanced it may be.

Yeah, that's true. Teslas have a front-facing long range radar and multiple ultrasonic sensors around the car for close range detection. Like most modern cars. But they are there just to avoid hitting anything, but can't be used alone for driving autonomously.