There are plenty of roads that have 75mph speed limits and there is even a road in Texas now that has a speed limit of 85mph.
If the flow of traffic is legally doing 75mph and an MV is cruising at 45mph, then I would say that the MV is presenting the potential danger because it is the outlier. If that same MV could travel 60mph then the potential danger has significantly been reduced because the other motorist are only flying by you at 15mph instead 30mph (relative speed). Considering those relative speeds, imagine a car going 15mph and runniing into the rear of a parked deuce. The damage to the car would be substantial but the driver would probably be okay. Now imagine that same car running 30mph into the back of a parked deuce. The damage would be much worse and the driver would probably sustain serious injuries. There is a big difference between the impacts at those two speeds. Also, the likelihood of a rear end collision occurring is probably lower for the faster MV because the other motorist would have a slower rate of approach (therefore more time to react) on it than the slower MV.
If someone runs into the back of someone, it is NOT the fault of the vehicle that got run into, but the rearender for NOT driving ahead, people run up on the rear of vehicles all the times thinking that they can change lanes at the last minute and keep going only to find out that that can not happen and have to get on the brakes real quick, sometimes not quick enough.
With the logic of Mvs going faster because people want to be gofasters, is the
same logic that says DO NOT PARK A DEUCE ON THE STREET BECAUSE IT MIGHT GET HIT BY A CAR Doing 30 MPH and strain damage and the driver hurt. Da, it is NOT the parked trucks fault it got run into, no more then a MVs fault going down the road, that gets rear ended, it is the persons fault that ran into it, there is a million reasons why the driver hit something in FRONT of them but in the end it is there fault, AND there fault that they got hurt and damage done to the vehicle. In today's world, the ONLY way to guarantee from getting rear ended is either park your vehicle in a locked one vehicle garage or go faster then anybody else, which will most likely turn you into a REARENDER
Remember SHOOTING IRON died NOT BECAUSE the speed of his truck BUT because someone was going fast and NOT PAYING ATTENTION