In film and TV, whitewashing has a long history. White actors played Asian, Native and Black characters in makeup for much of the 20th century, as with Mickey Rooney's role in "Breakfast at Tiffany's" in 1961. Recent examples include the casting of white actors as Asian characters in films such as "Ghost in the Shell" in 2017.
Whitewashing also happens in history. In 2015, a McGraw-Hill geography textbook used in Texas described enslaved Africans brought to the US as "workers" and "immigrants." The publisher revised it after a parent, Roni Dean-Burren, posted the page online. Confederate monuments and the Lost Cause myth recast the Civil War as a fight over states' rights rather than slavery.
Whitewashing matters because the stories a society tells shape its policies. When racism is written out of history, its effects today look natural or self-inflicted.