They do absolutely nothing to remove liability from the truck driver/company. If a rock falls from their truck and cracks your windshield, they absolutely are responsible for any damages.
Rather, their sole value is to convince drivers that the trucking companies aren't at fault, so that drivers whose vehicles are damaged from falling rocks erroneously elect not to press charges or pursue damages.
If you are tailgating directly behind a rock truck with a big sign "stay back 200 feet" for an extended period of time, or end up right behind the truck because you're in a big hurry, or because you thought you could squeeze through an empty lane, a good lawyer could absolutely argue, successfully, that you are at least halfway responsible for the damage, if not 100%.
Or did you mean you’d seek out the ceo of the truck company and give them a black eye?
If it's random gravel from the road it's more understandable. But even then the driver is very much responsible for the mud guards on the truck they are operating, just as the police would write a ticket to the driver for worn down tires or broken lights.
