Tesla's position is…
Tesla's position is ludicrous. Look you can test this out for yourself. The sink in your kitchen is stainless steel. Your cutlery is probably stainless steel.
Get some environmental iron oxide AKA steel wool. Leave it sitting in the bottom of the sink and leave a fork there too for good measure. Make sure that they're a little bit wet. Leave that unintended for a couple of days. There will be rust on the stainless steel sink and rust on the fork.
This is because where the iron oxide from the steel wool aka the Environmental contamination touches the stainless steel it forms a new alloy. And that Alloy can rust. By scrubbing you can clean off that 2-day buildup of rust. But you'll probably notice little pock marks in the surface of the sink and the surface of the fork where some of the iron oxide bound with and consumed the steel. That's permanent damage to and degradation of your sink and your fork.
The environment is filled with flying rust. Particularly roads where rusty cars travel. It is inevitable that environmental rust dust will settle on your vehicle and if it's wet it can start making visible marks within a day. Make no mistake. The instant the mark becomes visible you've already lost a little bit of the metal of the vehicle. Those micro pockmarks. And of course those indentations make it easier for the next time more rust to settle.
This isn't a problem in your kitchen sink normally because you are generally not foolish enough to leave steel wool sitting wet for a couple of days. Also you regularly wash out the sink. But cars especially trucks are meant to be parked outside in the environment and driven in the environment. Dirty environments. Environments where there's lots of rust. It is impossible to find a place where you can drive a truck that will not be affected to some degree by Environmental rust. And the only real workable solution to this is to meticulously clean each and every spot the instant you detect them.
Are you the kind of truck owner that likes to clean your truck with a Q-tip?
Daily?
I'll give you an example scenario. You park your truck in the driveway. You don't even drive it anywhere. Nonetheless other vehicles drive by on the road and gradually the rust settles on it. Overnight condensation forms and the moisture combined with the settled flecks of iron oxide are all that it takes to make little brown spots start to appear on your pretty pristine undriven truck will be speckled by morning. And this will happen every single day.