No manufacturer has it all figured out IMO
I still drive a Toyota and a Few Fords
My Toy has some rust on the frame that worries me a little
Wifes Mercedes has its own issues
Fix a whole lot of Duramax's these days
They tear up front end parts faster than an old Ford

 

Did you have a battery over the frame on that side? I would expect maybe to see that on the passenger side instead, coupled with salted roads.

I vote for a frame swap too because if it is that bad there, it probably is just as bad near the spring hangers.