In brief -- CORROSION is a scientific process, plaguing industries and destroying items of value. As a result, it causes headaches, stress and financial losses. To that end, erosion protection and other preventive measures are obviously a necesity in order to minimize such deterioration.
RUST is iron’s OLD HABIT. It is the byproduct of iron and moisture, is inexorable, and stopping it is hard work. Unless iron is placed in an atmosphere containing literally 0% moisture, it will rust. Such places do not exist with the exception of labs and testing facilities.