Yep. I remember being driven around roads like this with a friend with a high performance car who knew what he was doing, so could go what seemed like a terrifyingly high speed to me, but was perfectly safe for him. Then we hit some other cars going slower and he just followed at the same speed, infinitely patient for someone with a thirst for speed. Just completely happy to adjust to the appropriate speed for the situation.

People who know those roads drive fast, indeed, but it is not safe.

Visibility is poor and you cannot safely go through a bend at 50+ mph when you cannot see what's beyond it. There might be a stationary vehicle, a horse, a cyclists, even a pedestrian and you wouldn't know or be able to stop in time. This is how lethal collisions happen in those roads.