Speaking of the wrong actor in a part, I've never gotten over Pacino in Scent of a Woman—a role that absolutely, positively should have gone to Robert Duvall, I don't care how long they would have to wait for him. Duvall is even married to a South American tango instructor. Al just didn't carry off the military officer thing, IMO.
And I totally agree with you about “white” culture. There are marked differences from one of the original tribes to another -- the Celts, the Normans, the Etruscans, the Romans, the Scots, the Angles, the Saxons, the Slavs, the Teutons, the Norse, etc. Even today, the Catalonians are trying to break away from the rest of Spain.
However, the same is true of African-descended folks. Their tribal differences and ethnicities run a wide gamut, but they are all lumped under one label, “black.” Just goes to show that skin color is not the issue. Culture is.
Other examples are the Asian and Hispanic/Latino categories - each with many unique cultures thrown together into one box. On the other hand, some families have lived in the U.S. for so many generations, they cannot trace their origins to a single country, so they identify as a color. They do not understand those of us whose ancestry traces back a few generations at most to one country. Then again, the same could be said for Italians in America. I remember the older Italians identified with their own regional groups.
Back to the movie, yes, I can picture Katherine Ross as Kay. I never watched Scent of a Woman - only a scene or two - but I could picture Duvall in that part, too.
Also, I agree with you that Sofia Coppola fit the role of Mary, at least much better than Winona Ryder ever could have.