I’m sure there’s a ton of price-point economic reasons for it, and engineering ones, but it kind of pisses me off that cars haven’t used even more non-ferrous materials already. Knowing the second most expensive purchase you’re likely to ever make in your life is just slowly rusting year after year is kind of maddening.
And yes, aluminum can/will corrode, especially if it’s joined in certain particularly nasty dissimilar metal combinations, or God forbid, exposed to mercury, but in general, as compared to mild steel, carbon steel etc. in general outdoor applications, it performs infinitely better.