My sales department tried charging the contractors for the mud and freight separately for a very short time. Freight was always included in the price/yd, we had zones from the plant that determined the freight involved. Some of the contractors bit for a very short time, but they determined as I did before the experiment, that the 5 minutes per yard we gave them to unload was cheaper than the cost of the material plus the cost of the truck from plant to plant by the minute. End experiment.