|Ste. Elena, Costa Rica, near Monte Verde|
Here's the best example that the engineers are designing road speed deliberately: The steep roads up the mountain slopes are unpaved and rocky, even as they are generally well-maintained. Go too fast and you get a very rough ride. Therefore cars tend not to careen off the road into the abyss, even without guard rails, or emergency lanes, or concrete barriers. Yeah, it's dusty, but no one dies.