The speed limit should reflect the reality of the road. No, you shouldn't go around tomorrow updating all your speed limits to 85% percentile graded and then try to redraw the roadways to traffic shape to desired speeds. You would do the latter first, then update your signs.

Except in most places, neither is happening. People are driving dramatically over the speed limit because that is the natural speed of the road, and no attempts to change the actual speeds of traffic are happening because they cost money.

So people get to die for the multitude of reasons the article outlines because of political deadlock.