Some of us have to pay for our petrol, tyres, brakes and servicing all of which increase in cost as the sped and intensity of use climbs. Add to that the fact that not all roads are fully dry with perfect visibility 365 days a year, free of mud, bends, children with other hazards and that includes motorways, so it is clear that there is a vanishingly small case for always driving at the maximum speed allowed. I tend to drive at anything up to 5 mph below the speed limit in normal urban conditions avoid rapid acceleration and allow stopping distances in front of my vehicle - I would like one behind as well!
When approaching my sharp left hand turn off a 40 MPH road I guess I have several choices, blast long at 45~50 as many would like or shave the 40 Mph by 0.00001 mph below 40 until the last moment and brake hard, or signal just after I pass the last turn before mine and allow my speed to fade until I complete the speed reduction to the 10 ~15 MPH required to safely turn into the sharp turn (is a 40 limit even right?). As for the stupid faction that leave no space between them and my boot, they do deserve any and all contempt for not observing signals, road conditions and having zero judgement.
The idiot rushing to the airport, 60MPH in the 40 limit with torrential blinding rain on near bald tyres might recognise his error, shame his passenger ended the trip there and then and another was out for more than a month. I felt sorry for the driver going the other way, put in hospital and her car destroyed, but she was only going 30 or so in the appalling conditions or was she guilty for getting hit on her side of the road?
A speed limit is supposed to be a maximum speed allowed, not a minimum cruise speed.
There is never a valid reason for tail gating, however there are no obvious ways to remove the hazard from one's own road space, that is the space required in front of and behind your vehicle to allow hazard management. If fog lights remind a dumb ass that they are being stupid, better that than they cause an accident.
Some commercial vehicles are governed to less than 70 mph anyway and a number of vehicles are limited by other means to a lower speed.