The speed limit needs to be indicated in order to be valid so that’s a completely ridiculous point you’re trying to make.
If people don’t pay attention to their driving they need to be penalized for it because no matter the road design, they’ll commit infractions and no matter the road design, speed limits need to be enforced otherwise they become suggestions.
See another of my comments with sources proving that speed cameras do reduce speeding by a wide margin, proving that drivers pay enough attention to their speed that when they fear they might be penalized for speeding, they slow down.