This is a frequent trope employed in places with comically inept snow preparedness - like the Pacific Northwest - ignoring the existence of automatic carwashes. With how many persistently dirty Subaru Outbacks I've seen on the 5 I question if they know this alien technology exists.
It's not the salt alone as far as I understand. It's the salt, the moisture, the dirt, the micro damages/cracks, temperature changes all working together to foster starting points for corrosion on surfaces or crevices. Leaving all this on does give it time to work.
Regular washing dies remove some of the culprits (salt, dirt,...) thus reducing the attack vector on the surface. Wax might even add some protection.
(I read the "time is not the issue" comment but am not sure how to understand it, surely time plays some role in it, else the corrosion should start immediately at contact with salt?)
To elaborate, the failure rate does not change with time, but with some other stressor like temperature. The failure distribution may be modeled as a random process, instead of a time-based one. An exponential failure distribution is an example of a time-invariant process, while a Weibull or Gamma distribution would be time-variant, because the failure rate changes with the age of the item.
