Is it just me or did the article at no point explain why medical models produce biased results? I seems to take this as a given, and an uninteresting one at tha

Is it just me or did the article at no point explain why medical models produce biased results? I seems to take this as a given, and an uninteresting one at that, and focuses on trying to correct it, without explaining why it happens in the first place. Yes, those models could use race as a shortcut to, presumably, not diagnose cancer in black people for example, but why is the race shortcut boosting model training accuracy? I am still none the wiser.