Truck deadheading occurs when a semi-truck drives with an empty trailer. This happens when the trucker has dropped off a load and needs to pick up another load elsewhere. Driving with an empty trailer can be dangerous, as the truck is more prone to accidents and rollovers, especially in windy conditions. You may have seen these empty trailers swaying on the highway.
CDL drivers are trained to haul cargo, not to drive empty trailers, and less experienced drivers may struggle to control them. Moreover, some drivers may not be paid for deadheading, which can incentivize unsafe driving to minimize the time spent driving with an empty trailer. Truckers try to avoid deadheading, and it would be better to pay them per hour instead of per mile.