I think you are still off about the privacy aspect. At the source, a return from a single radar pulse is pretty uninformative. But a single pixel on a camera sensor is also uninformative. Even at the source, an aggregated set of radar returns is still a privacy concern on the level of an aggregated set of camera pixel values. Not operating in the light domain doesn’t make the privacy concerns go away, it just means that laypeople aren’t going to understand the risks as intuitively.