bikeportland.org reveals an alarming movement in St. Charles county, Missouri (40 miles west of St. Louis, including portions of popular bike/ped Katy Trail).
The solution is clear... drop the speed limit in spots where visibility is lowest/danger is highest. Add warning signs to these spots. Educate motorists.
Anyway, bicycles are not the only potentially slower-moving vehicles on these roads. What about farm equipment, or horse and buggies? Can you imagine the flak lawmakers would get for trying to ban farm equipment on two-lane highways? It would be political suicide.