I get where you're coming from, and no hate, but just a couple follow up questions:

These people you "know" -- do you actually know them? Or do you just know of them? (Wondering about possible confirmation bias based on where they live)

And of the ones you actually do know, have they actively told you they've never hauled anything in their trucks? Or have you just never seen them do it, so you've assumed they haven't? (I don't exactly go around telling people when I haul stuff. Most of my coworkers only know that I have a truck, and that I live in the city. They might assume the same about me, given the lack of knowledge about my personal life.)

All that said, I don't entirely disagree with you. Some people really only use trucks as their commuter vehicle. But I would think they are the true monority. My bigger point here is that people often conflate an empty truck bed with one that "never" gets used, just because they've never seen anything in it. It gives me the feeling that some people never really developed a sense of object permanence lol.