[rotorwrench]

Aircraft have been using CRES type tubing since the WWII era. It turns brown over a fairly short period of time. It's certainly too much work to keep polished. The systems also need very good support due to the weight. They erode more than corrode but tend to crack when they get thin.

Model A cars already had issues with the exhaust manifold tending to slump down on the heavy end and a lot of that is due to the weight and arm of the exhaust pipe and muffler. Ford should have supported the pipe in front of the muffler as well as behind but they never considered it and issue. They likely didn't figure that so many of these cars would survive as long as they have,