Here in Ohio the speed limit is generally 70 mph on interstates. I drive I-71, I-75, I-77 and occasionally I-90 and by far the vast majority of trucks are running 65 or just under. We took a medical trip to Boston about a month ago and was surprised that even on the turnpike a lot of them still ran this way. Not all, but my far the majority did. I am assuming fuel mileage plays a big part also to run that speed. Not sure if a lot of companies govern their trucks down or not. Seems like more and more are doing everything they possibly can to squeeze out the most mpg possible to cut their costs. Googling finds lots of information on fuel savings by running 65 or below, can be any where from 7% to 14% savings. That is a big difference when you are talking fleet operations....
Looks like more and more companies are using software to monitor driving habits of their drivers. As always, the government is looking for ways to cut emissions and fuel usage down, so maybe mandated a lot in next few years. Unfortunately in real life it isn't as easy to make money in trucking as it is in ATS or ETS2.....