Casting people as “goodies” and “baddies” might be rational. Suppose humans have a need (or desire) to predict another’s actions, or consequences of another’s actions.
Humans do not have all the time and resources in the world to evaluate each individual they interact with, directly or indirectly, so they may choose to use prior probabilities to model their world, as a shortcut.
It seems plausible that if this model of the world developed by shortcut is sufficiently accurate, then it would be rational to use this approach because the time and resources conserved can be better directed elsewhere (for the individual’s benefit).
Of course, erroneous or excessive use of prior probabilities may lead to negative effects for societies (possibly visible only in the long term).
That’s an instinct we can and should avoid in general debate though.