While I agree that farmers can have specialized vehicles for different tasks, not all do. We farm sheep, pigs, chickens, and ducks and do not have specialized equipment. We don't even have a tractor. I also don't disagree that people who don't have a use for trucks don't need them, but I wouldn't go to far as to say they shouldn't have them. While objectively worse for the environment than a vehicle more suitable to their lifestyles, it's a slippery slope (as we've seen) once we start legislating morality.

Bottom line: if we didn't operate a farm business, we wouldn't have a need for or the desire to have a large truck. More likely, any truck at all. We certainly wouldn't have one to park in the driveway of the suburban house we would probably live in. It's just impractical, but not everyone is gifted with innate pragmatism.