I cannot speak for other states, but NY requires a driving test and has police regularly enforce traffic violations too. None of this supports the idea of setting highway speed limits below the 85th percentile or even having high way speed limits. It instead suggests that we should copy the Germans.

As for gruesome accidents, there will always be Darwin Award recipients. Trying to prevent them from earning their rewards is a foolhardy task. I believe the maxim is that the moment you make something idiot proof, the world makes a better idiot.