For example imagine some ML algorithm that predicts the potential value of a customer (or their likelihood to steal from you) as they walk in the door of your business. How do you remove the racial bias from a system like that when racial biases exist in society that result in the average White person being in a higher socioeconomic class than the average Black person? The ML algorithm will tell you White customers are more valuable than Black customers. It is doing exactly what you told it to do, but the end result is that Black people get worse service in your business.