Which is kind of crazy to me. We beat the heck out of utility trailers and goosenecks at work at full GVWR and typically we replace the axles several times, and everything else many times long before we ever crack a frame. I don't think we have replace an actual gooseneck trailer. (Just every part of it) in 11 years and that's 11 years of oilfield roads every day. We actually upgraded from 20k axles to 24k lb axles on most of them.
Go compare the thickness of gooseneck to a camper frame.
Business users are less price conscious compared to a private owner. A business plans to use a trailer to make money so the higher upfront cost for better materials is worth it to avoid issues.
Camper manufacturers could absolutely build a camper that could take any abuse you could throw at it. It would weigh 40,000 lbs and cost $500,000.
Nobody would buy that. Campers are 100% a luxury vehicle that a large majority of owners can't actually afford to begin with. They want a trailer they can pull with a common pickup truck so it has been be light weight. Thats how they end up with frames made of 16ga steel. Then they want it to be even lighter so they build the walls out of tooth picks and single ply toilet paper. The appliances are all built in China by 1 company that bought all the independent manufacturers and outsourced it to keep prices down.
The trailers are mostly built by workers on an assembly line working for not great wages with no incentive to actually care about quality.
People then go ripping down the interstate with their paper shack at 85 mph and can't understand why the wheels are blowing up and the walls are all cracking.
I had a 2018 Grand Design travel trailer. I traded it in for a 2022 Forest River 5th wheel toy hauler. Looking under the cabinets and inside the underbelly they are built exactly the same. The wiring is a shit show and the plumbing isn't much better.
I had more issues with my Grand Design than I do with the Forest River. The FR is 50% bigger and a Toy hauler for the exact same price as my GD.
I'd rather buy the cheaper Firest River and used the saved money to upgrade it myself. I've already started replacing the cardboard/MDF cabinets with custom built ones made from actual wood.