From what I understand, it's the result of the lack of US vehicle safety standards. Or perhaps a loophole in them. Trucks have different safety standards than

From what I understand, it's the result of the lack of US vehicle safety standards. Or perhaps a loophole in them. Trucks have different safety standards than cars, and car manufacturers find the car safety standards annoying, so they started marketing trucks to consumers. They don't have to obey the same regulations as cars, and yet because they're light trucks, they don't require a commercial driving license. That's the loophole through which the US car industry managed to drive their entire industry.