Sadly mistaken on that one my friend. It may not be as bad as in the east but there are all sorts of rusted out vehicles around here. They use far far more salt/ice melting compounds on the roads than they used to. Plus with the stupid body design (dirt hang up places) of many vehicles it is common to see rust holes on 8-10 year old vehicles.
Ya, it was only meant as a relative thing - sorta like the cost of machinery in the east vs the west.
There is no doubt that the difference between East and West is huge, even with the salts and crappy body designs. But I agree that it's still a problem.
The real point is that putting a car in a garage out west is not going to kill it. But doing that here in the rust belt is an invitation to disaster without rust proofing and regular maintenance.