The answer to this questions points to an idea that is central for achieving Buddhist Enlightenment. This is the idea that mind has a built-in tendency for reification, stereotyping, and overgeneralization; that all our suffering and confusion comes from this tendency; and that liberation from suffering and achieving clarity requires liberation from that.
Mind has this intrinsic function to delineate entities. As it observes the facts, it tries to connect them and create a consistent picture, a story, a model that explains the cohesion behind the facts. I suppose doing so has an evolutionary advantage, because constructing a model gives us a way to predict the model's future behavior.
However, this method has its flip side - which is, we tend to equate our models with reality. Indeed, outside of models there is no experience of the world. So, naturally we tend to assume our models are correct, and as long as they come from experience and have some forecasting power, we tend to attach to them. This gives us a quick way to make decisions about the world. We see something, we recognize it as one of the previous things we have seen, we classify it, and based on that automatically pick the reaction. It's a very efficient mechanism, great timesaver. Imagine if we had to reevaluate everything from scratch every time we saw things.
At the same time, assuming our models are reality gives rise to a sort of perceptual blindness. We end up seeing with our brains, not our eyes. We jump to conclusions. We become stubborn. We are judgmental. We are superficial. We are tone-deaf and blind to nuances.
So getting more details for our models - any details really - increases the chance to get some evidence that will uncover the holes in our model-building. This shows up in your example above, when getting a sense of persons's background, facts from their personal storyhistory, can helps us see beyond our mind-made model of them, and into the real person.
Buddhist Enlightenment is to go beyond models. Realization of "Emptiness" is seeing that all our models are mind-made. Buddhist tolerance, total acceptance, humbleness, is the social application of this realization. Buddhist suchness is the emotional state we get when we learn to live in a non-stereotyped inner world, not dragging any models from the past. Buddhist meditation is to see into our modeling process, and learn to go beyond that. Buddhist liberation is to liberate from the oppression of models.