A lot of the supporting cast in Spiderman are non-Caucasian though. The Ancient One has been a rare misstep for Marvel when it comes to their casts so far. Whitewashing happens because studios want names in their films that people recognise (so Scarlett Johansson is the Major rather than, say, Rinko Kikuchi, the only Japanese actress who has possibly any name recognition in the US). Nobody wants to take punts on unknowns or lesser known actors. So you get a vicious circle where non-Caucasian actors never get a chance to make a name for themselves and studios use that as an excuse to cast another white person people have heard of instead.