Originally Posted by rubber soul

Honestly, I don't know. It could be that Jolson was just a product of his time. In the 1920s and 1930s, it was in style to make fun of minorities, particularly African-Americans, so no one ( or at least no white persons) batted an eye when someone would go on screen in blackface and do some ridiculous caricature. It was an era when the KKK was popular enough to control the government of Oklahoma for a time. Racism was more obvious in the movies but there are plenty of racist songs from the early period of recording as well.