Doesn't make it right, but until everyone chooses to drive the speed limit (never), it's actually safer to just go with the flow of traffic.
The two 4 lane highway options I can take between Illinois and St Louis are both 55mph zones. Morning traffic runs between 65-70mph.
Once on the interstate outer loop in St Louis (60mph), traffic flows between 70-75mph.
The people getting pulled over are the ones doing 80mph and above, weaving in and out of the flow, not using their signals, etc.