Just because he lives in the rust belt it isn't automatic... Based on his description of use seems excess but typical of todays autos. For instance I have an '01 3500 Dodge with absolutely zero rust and you don't any more rust belt than Western NY. Driven very minimally in from oct to April, kept out doors, 220000mi, Additionally I have a '05 magnum driven daily year round, 150000miles again no rust. My guess they have changed their pre-paint prep. Again guessing, due to its increased popularity phosphate wash vs a primer dip may be the root of this issue. Phosphate is body-less (cheaper, less costly to apply and doesn't run if applied wrong) where a primer dip had substance to it. It offers a better seal where paint may not be able accumulate. Add the lack of sealers and foam sound/stiffening materials rust is sure to happen.