There’s a road near me that clearly should be a 50 but they can’t be arsed so they’ve just slapped to 30 limit on it. It’s long straight has no hills has two lanes and a central reservation, it’s a perfectly safe road.

But at 150 mph that road would be a death sentence, because it has a very very slight curvature to it, so slight that you barely even notice that you are going around the corner your brain just automatically has you turn the steering wheel ever so slightly. At 150 though the motion would probably destabilize the car.