If all cars went the speed limit then cities, towns, and counties would lose speeding ticket revenue. I suspect the money would cause attempts to force safe speeds to fail. On the flip side there's a certain amount of freedom inherent in being allowed to speed. So, it seems like there might not be enough support, on any side, to make this feasible.

Around here, going the speed limit typically means going slower than the rest of traffic. If all of our cars forced us not to speed, I wonder if speed limits would naturally increase to safer limits. I also wonder how much of what I just said is a result of Prima Facia speed limits here.