The lack of distractions can be a problem in and of itself
Long Haul trucking companies consider having a radio/CD player/etc in the truck to be a positive safety feature, the lack of any distraction for long, monotonous drives can result in drivers effectively being mesmerized by the constant scenery, causing them to be very slow to react to new events. Having the slight "distraction" of a radio can prevent this and reduce the chance of accidents.