My thoughts on the problems with newer vehicles.... not in Toyota's interest to make a vehicle that will last 20 or 30 years anymore.....they could make a fantastic vehicle with little or no rust issues for at least 25 years... the tech to do so has been around for years.....The state of those rear ram shrouds, the blown AHC pipe, and the few rusty bits of brake pipe are imo signs of Toyota bean counters cutting back on rust prevention coatings on newer trucks.
I do wonder if Toyota were affected by steel supplied from Kobe that was not to spec.... it could explain sudden rise in rust issues and for sure Toyota would never admit they had an issue