Why does Dodge go cheap with their steel?

I used to work in a plant that made automotive stampings for the Big Three.
The oem can specify steel made to a certain "recipe". They picked stuff that was cheap. Some cheaper than others. Take the Chevy Vegas for example. They rusted out before they got to the dealer!
American cars got better when the Japanese made a better product and the Big Three had to step up some. Japanese cars were more expensive, but the Big Three knew people would spend less and they didn't make them too much better. Japan didn't make full size pickups for a while, so the Big Three didn't worry. Now you can buy a full size Japanese pickup, so I expect American pickups have improved, like the cars did.
My wife's '07 Accord has zero rust issues (no issues, for that matter), and we live at the Jersey shore. As long as people still buy stuff that isn't made well, they have no incentive to make them better.