To be fair, they're really not that different. A common definition for SUVs, to my knowledge, is essentially just a passenger car built on a light truck chassis. Lots of these modern trucks have a full set of front and back seats and a relatively small bed (compared to the size of the vehicle anyway), and further, many are used by people who almost never actually haul stuff in it. In such a case, such a truck is basically getting used as an SUV anyway, just shaped like a truck because lots of people like trucks I guess.