In florida, I will say when it truly pours like that people do tend to drive extremely slowly and turn on their hazards. Also, sometimes these storms just appear out of nowhere. Over the summer I was driving from the Vero beach area to fort lauderdale and on the way to Vero beach, clear skies and on the way back there was an ENORMOUS storm that flooded streets and you couldn't see crap. It just happens
Unless it truly is "once-in-a-lifetime", or very brief, you cannot just stop and give up. To be a viable replacement, a vehicle must (as a human driver would) continue to make progress even in extremely adverse conditions. The progress might be much slower than usual, might be a re-routing (back up away from floodwater and go elsewhere), etc.
