But how can we find out if a company uses ML in a non-discriminating way? If we cannot see it, and check it, then there is no incentive for companies to use it. My guess is that at most companies spending time on making an algorithm non-discriminating will be viewed as a waste of time and money.
Banks are built on trustworthiness. Having your bank's name in the headlines for discriminatory practices can have a severe negative impact on trustworthiness. They have a whole teams of people devoted to this topic and every year at most banks every employee has to learn about, "reputational risk."
Having worked at big banks for over a decade now I am 90% certain that discrimination by banks at this point is primarily due to carelessness.