Pretty much every form of motorsport in the US runs in the rain except for oval racing. It just doesn't work so well there. CART, AMLS, SCCA, and most all other road racing organizations do run in the rain. I have even run a go-kart race in the rain before.
And generally, we don't sauce in nitro here either and that was not what your original statement against Americans was about anyway so why bring it up now?