If the interview task is objective (come up with an algorithm for this problem and derive its big-O complexity), then feedback is less required, because the can

If the interview task is objective (come up with an algorithm for this problem and derive its big-O complexity), then feedback is less required, because the candidate knows exactly what skills they should improve. Unfortunately, many people today think objective interview tasks are "brain teasers", "toy problems", "instead ask me how I can add value to business" and so on.