If you are a commercial driver of a large truck, any mistake that you make has the capacity to have a more devastating effect than a driver of a passenger vehicle can inflict. This is why you are held to a higher standard when it comes to having alcohol or drugs in your system when driving.
There would not be much trade between states or food on the shelves of supermarkets without trucks, vans and commercial vehicles. Even in a state with as many transport options as Texas, truckers take the lion's share of goods to market. However, the size and weight of trucks can make them deadly when they are out of control.