If everyone played by the book and stuck to the 40, the TMs would need to reduce the amount of work given to any driver, they would then need to employ more people and with fewer drivers around they would probably have to offer a little better money. Sticking to 40 could result in more money for less work.
So the question should be; are the flat-to-the-mat boys depressing the pay and conditions of those not too fussed about being the bosses favourite?
wanting the speed limit raised, turkeys voting to have xmas on the 5th of Dec.