Let them drive in fog and suddenly they can’t even see clearly visible emergency vehicles.

That article you linked isn’t about self driving car. It’s about Tesla “autopilot” which constantly checks if a human is actively holding onto the steering wheel and depends on the human checking the road ahead for hazards so they can take over instantly. If the human sees flashing lights they are supposed to do so.

The fully autonomous cars that don’t need a human behind the wheel have much better sensors which can see through fog.