One of the big complaints of tow operators is that drivers will not "SLOW DOWN & MOVE OVER". Tow truck operators should never depend upon approaching motorists to slow or move. This is the primary reason that many states have courses in Traffic Incident Management. TIM is taught free in Virginia by the Department of Transportation. A tow truck is not an effective or safe vehicle for traffic control. A police car is not much better, but the lights on a police car do communicate authority while amber tow truck lights do not communicate anything more than a road maintenance vehicle, a tractor-mower, a dump truck , road construction equipment, or many other vehicles. That is why in incident management, many cities and states have gone to the use of fire trucks or truck mounted attenuators (crash barrier) to protect accident scenes. Fire trucks are parked so they cover two lanes of traffic and at an angle. If a vehicle drives into the accident scene, it will hit the fire truck and the angle of impact will help drive it away from the working scene. An attenuator truck has a collapsible barrier that can be lowered and it is parked directly in the lane that has been closed; if it is struck, the barrier collapses and absorbs impact. Neither approach is perfect, but they both greatly reduce the risk of serious injury or death.
As mentioned, a tow truck's lighting means nothing to approaching traffic and for this reason it should not be used as part of traffic control. In TIM training, tow trucks are supposed to park ahead of the barrier vehicles and off to the side until they are cleared to remove damaged vehicles. Once the hookup has been made, the tow truck is to leave the scene. Incidentally, this is a good moment to remind tow drivers to NEVER get behind a disabled vehicle and push it out of the road. If the average inattentive motorist slams into him, he will probably have both legs cut off or be killed.