I’m just telling my experience. I’ve packed for a lot of trips in a lot of different vehicles over the years. I’ve never pulled out a tape measure, but I haven’t noticed the big difference you’re talking about with SUVs.
One other thing, we have a rooftop carrier. I just realized I haven’t used it in years. That’s partly because we have fewer kids at home now so we can fit everything in the car, but it’s also just a pain to reach up above the roof because it’s taller than back when we had minivans. So that’s another consideration when you are trying to move a lot of stuff.
Also, the 7 to 9 seat comparison is a little disingenuous. Most SUVs seat 7 or 8, and most minivans seat 7 or 8. A front bench seat is rare in SUVs (and really rare in minivans).
And your comments about only getting a minivan because you can’t afford something better are pretty condescending. You and I might be able to afford whatever we want, but cost is a factor for most people. I can afford to get either one, and we have gotten SUVs for the last several years because that’s what my wife wants, but if I had a choice, I would choose a minivan. Go figure, people have different opinions than you.