I don't know, I have two cameras (eyes) and no radar (my bald head appears to be a radar dome, but it is not) and I do pretty good.
Me = developed vision software that scored 112 IQ on Raven's (that's ridiculously good, if you are in the know). I think it is mostly a software thing that will be figured out. To be clear, I do not disagree with keeping lidar / radar; although it creates cross dependencies and complications that makes software development and troubleshooting more difficult.
If it can be solved without radar/lidar it would be better for costs. As you said, it is just a software problem. We cannot expect $100k+ worth of sensors and hardware to be adopted by the average person. Especially if it requires frequent recalibrations and has a short lifespan (lidar).
So far FSDs vision based is doing fantastic. It would be nice if it was further along, but it is moving.
Robotaxies, I get the necessity for these expensive sensors, there is no human available to take over in the event of an issue.