The Driver controls the vehicle’s steering, braking, and throttle. The Driver can also shut off the vehicle’s engine. The Driver is focused on controlling the vehicle.
The Safety Officer’s job is to make sure the field is clear of obstacles and other people, and to stop the vehicle if an unsafe condition arises.
The Safety Officer has a separate control radio, and can shut off the vehicle’s engine, apply the vehicle’s brakes, and disconnect the vehicle battery after a crash.