People who drive a truck for work aren't going to crash it into things all the time, what are you even talking about? Do you regularly crash your car into things while driving it? Like on a daily basis?

Like..you get that mud and dust just wash off, and the reason to wash them off is that once dried they can mess up the paint over a long period which then gives you a rust problem you really don't want?

The people I know who drive trucks are doing things where constant small bits of damage are inevitable. Think kicked up gravel, tree branches scraping against the body, unintentionally bumping up against the truck with equipment, etc. Damage is frequent enough that it’s one of the reasons they find buying a new truck difficult to justify and would rather buy something that’s got some visible wear and tear on it already.