Why cars rust

My theory as to why north-west U.S. cars ( non-desert areas of Oregon and Washington ) don't typically have the rot issues as much as a southern Ca. car would --- especially a coastal / beach city car --- is due to the consistent rain . This consistent flow of water certainly washes-out the drains , window channels , etc. , thereby not letting any impurities stagnate in nooks and crannies .

As I've mentioned before ( please bare with me if you've read this before ) , cars in a Mediterreanian [sp?] climate such as southern Ca. are subjected to :
- Blast Furnace heat ( look at that pilot 1967 Valiant sedan in Arizona !! )
- Dry , shitty , windy days ( Santa Ana Winds )
- Cool / Cold , damp winters ( been raining for 4 days straight as of today !!! )

The heat kills everything that's plastic , rubber , etc. ; the dry windy days kick-up dirt , dust , leaves , grasses , weeds , sand and other grainy **** , and dispense of these things in window trim , under vinyl tops , body drains , cowls , etc. , etc. ; then the cold , wet winters dump rain / cause fog , which the sand , dirt , leaves , etc. , retain , thereby causing rot .

Not sure if eastern Washington and Oregon have that same problem , as those are Arid and Semi-Arid climates ...