You have asked a question that, as you can see, stirs up a lot of debate.
My ideas are these:
When towing a utility or equipment trailer, one can adjust the load on the trailer forward or back to manage tongue weight. With a little experience, one can "eyeball" the load the trailer is placing on the TV and fairly effectively place the load in the right spot to keep the truck and trailer stable.
I realize this does not transfer any of the load to the front axle of the TV, but it keeps most of the load centered over the trailer's axles and off the the truck entirely.
With RVs, weight is spread all over the place. Yes, we can place any loose items we decide to haul inside the trailer over the wheels. But, the furniture, walls, and such can't be moved to manage tongue weight. For the most part it is what it is.
Most of the equipment trailers towed by bumper hitch are shorter than the RVs we are speaking of. Longer over all length means more distance between the rear axle of the TV and the trailer axles. This can allow more sway, as the trailer is a longer "lever" against the hitch point. Sway control helps manage this.
I would also suggest that RV's are towed in a wider range of conditions. I don't see many backhoes and trailers full of lawn mowers running 65 (or more) mph down the interstate. Most are in less dynamic conditions than found when towing our RVs.
I tow my Airstream with a Reese dual cam system.
I tow my small farm tractor on a 14' utility trailer with nothing but a ball, but carefully centered over the trailer axles.
Jeff & Cindy
'09 27FB Flying Cloud
'91 350 LE MH