> Would it not end up penalizing the exceptions?

Yup, but so too do credit scores in general. If Harry was unlucky, lost his job and missed a few credit-card payments, then his credit card will suffer regardless of whether he is now actually likely to default; the trouble is that he is the type of person who will default.

It's unfortunate, but that's what happens whenever one tries to categorize people. And it's unavoidable, even with extensive work in-person, as anyone who's ever been deeply disappointed or pleasantly surprised by a family member or close friend can tell. If Pete couldn't tell that his brother would steal his car, can he really be certain that a stranger won't default on his loan? All any of us can do is play the probabilities.