[crazygringo]

> but even in those conditions - especially in those conditions - one should always be careful to not drive off a cliff, or off the outside of an unexpected turn in the road, or into a fallen tree, or into a pedestrian, or into a stopped car!

Yes, but you're missing the fact that that's not always possible.

You can be as careful as any human being can be, going the speed limit (or slower in bad weather), but unexpected things can happen faster than human reaction time can allow you to avoid them.

And in the heavy rain at night, figuring out that the black patch of what looks like road a few yards ahead isn't darker asphalt because the road was recently resurfaced (as you might easily assume), but is actually the road entirely collapsed -- I'm not sure that would even be possible visually.

So "always be careful" isn't helpful here.