"The book" in this case starts with legal obligations under the Civil Rights Act, the Age Discrimination in Employment act, etc. A milquetoast 'well, I treat everyone equally' doesn't even come close.
Or, to use an analogy, consider interviewing someone who, when asked about their preferences and strategies for ensuring code quality, answers "I just write correct code in the first place". Even if they're correct in that statement, that's not the sort of person you want in charge of that subject, because most people don't work like that, even if they wish they could.