Double Standards 2

Why is it that everyone in a car has to buckle up (seatbelt, that is) while a truck (aka as lorry over here) can carry a sh*t load of people in the flatbed, obviously none of them with a seat belt?? Remember that the truck is usually open air (no roof), barely any protection on it's sides (no such thing as side airbags and had but a tailgate. Trucks were not meant to ferry people around. But it's ok to do so, but no ok to sit in a car without putting on a seatbelt. I wonder...