That simply isn't true. We have laws in the US that dictate fuel economy relative to the size of the vehicle. Car manufacturers realized that they could make bigger vehicles rather than make them more fuel efficient. That's the real reason our cars are so bloated

This is true; "light truck" is the classification.

Basically, it would have been annoying and more expensive for car manufacturers to meet the standards, so they just started producing and promoting a bunch of vehicles like SUVs that technically classify as light trucks and thus are exempt from them. American consumers are American and thus love dumb big things for the sake of being big, so that was a pretty good gamble.

Yes, there are loopholes for “commercial vehicles” that aren’t regulated as strictly, which is why pickups keep getting bigger and have such bad efficiency

It also creates weird counter-incentives, like no small/mid pickups. Manufacturers don’t want to build small to mid sized pickups because they would be subject to more stringent efficiency, emissions , and safety regulations, whereas large ones are not