You must be terribly unlucky, or I'm terribly lucky. Never had, or seen, plastic with any coating oxidizing against an aluminum wheel. And I do tend to get out a bunch.
Bill
Not against an aluminum wheel - my wife had a 2008 Lincoln MKX, wheels were steel with chrome plated plastic trim. Once it lost it's luster it was impossible to clean the brake and road dust off the wheels, and it looked like corrosion.