The problem with that collision is that neither the radar nor the camera saw the obstacle. To the camera it looked too much like the sky as you say. To the radar it appeared to be a stationary object and so probably an overhead sign or something instead of another vehicle. Once the car gets close enough that the radar's cone only includes dangerous obstacles then it starts putting the brakes but in that case it was too late.

In general, though, the art of combining information from multiple sensors is called sensor fusion and its a fairly well understood problem. Well, sometimes even good engineers make mistakes, see Schiaparelli and the saturated Kalman filter inputs, but we have a good idea of what those mistakes can be for different schema.

EDIT: Mistyped radar as lidar, fixed.