To be fair, there aren't many black people talking about racism in this book, either. But it does acknowledge that is because Jean Louise doesn't know any, other than Calpurnia and C's family. Also I think there's the difference that Go Set a Watchman doesn't claim, or can be perceived to be, about civil rights. It's about a young white woman realising how much or little she knows about some of the people closest to her in a time of change, which brings out the racism she missed before.