Rust is contagious

I went over my sons Ford covering minor rust here and there as theres so little paint on joins and seams and sharp edges .This car is just over 2 years old and the thin paint on rough edges just doesnt resist the elements .No paint on the engine block ,flat paint under the hood .My Volvo 740 is rust free and 18 years old my wifes is 20 years old no rust .My sons 240 is rust free at 18 years of wear and tear .We don't have salt on our roads so mainly GM and Fords rust.On a quiet day with clouds over head you can just about hear the GM cars rusting .I think my Volvos will just keep rolling when the Ford is rust bucket even if I do like the features and ride of the Ford its very remote not a car with feeling and feed back .So yes my wifes wants another Volvo later on now we cured the problem with hers stalling (wide spark gap ) as she prefers the comfort and safety as well as the cheaper part prices.