I've had new toyota pickups since 1978. If untreated, and living in the rust belt like I am...those toyota frame's can be toast in as little as 7 years. It's only in the last 20 toyota has made an effort to inspect them. Even this last tacoma I purchased, the dealer told me that toyota has done their part, but it's still up to you to keep the truck undercarriage free of road salt as best as possible.
I think until dana, their frame supplier gets orders to supply hot dip galvanized zinc frames, the rust issues will continue. After all every manufacture wants you to keep buying new trucks every 10 years, or sooner.