yup, the engine made today destroy the transmission made today way more easily than in the past. and i think you are right, so much stuff is computer simulated and then the real world tests only simulate driving around in hot and cold areas while towing.
talking to guys here who do those test mule driving simulations (we see the test cars for lots of manufacturers here in south texas. all painted up like zebras or covered in weird cloth looking things to hide their actual looks), they don't do anything but set cruise control and drive the set routes for their 8 hour shifts. and that is probably actually only 6 or 7 hours of road time because of breaks, refueling, etc. but the miles rack up and its driving in real life so the designers feel its real world driving.
the thing is, its not in traffic or dealing with actual stop and go, towing a heavy load in stop and go, or bumper to bumper driving flooring and braking.... normal real world driving some people do.
i actually see a lot of the truck testing here, occasionally cars. especially dodge and toyota. it will generally be three or four identical models with manufacturer plates with at least one pulling a flat trailer that has a large frontal load to simulate an rv (because of hte wind we have here).