It is not exactly true that nobody complains. There a lot of discrimination complaints to go around. But since we do not have means to open the brain and check

It is not exactly true that nobody complains. There a lot of discrimination complaints to go around. But since we do not have means to open the brain and check what was the reason for this or that decision, deducing motivations is hard (unless you are commenting on internet, where everybody knows everybody else's motivations and is not afraid to explain it voluminously to each other). It would also be hard with algorithms, so basically the approach seems to be "reducing the problem to one we already know" - i.e. switching algorithmic unscrutability for human unscrutability and hoping that humans would do better or at least in won't be worse than what we have already been dealing with for millenia.