Anyways, if this is true, it's a grim future then. Radar is incredibly trivial to interfere with.
One is the basic "environmental" interference with competing radar signals from other devices. Imagine how much more complicated this gets when a majority of competing traffic is likewise equipped.
But the other risk, which seems to be mostly ignored thus far, is sabotage. Can you design a system that is hardened not only against stray competing EMR but also against attempts to hack or vandalize your system into misbehavior or malfunction? For example, consider a terrorist plot. Or even a smart neighborhood crazy who wants the neighborhood kids off his lawn and neighborhood traffic to stop during his midday nap. Or, a British organized crime gang using stopped traffic to cover an escape[0].
This would be very difficult to train with ML, however. I'm sure there are other downsides I'm not thinking of
It uses many kinds of sensors. Yes I know about clutter, I've spent quite a lot of time in the radar industry. But by combining data from radars of multiple wavelengths, it becomes pretty feasible. Though yes, difficult.
We need to fundamentally redesign our road systems to accommodate self driving cars. That might happen... in 50-100 years...after we address the already crumbling infrastructure we have. For perfect, sunny conditions, like the roads in Nevada all these self driving startups are doing their testing, with straight flat landscapes, I am sure the tech can work fine. Rest of the country, maybe not so much.