Yep, it happens even in populations where everyone explicitly condemns racism.

The way it happens is everyone has a baseline of what they’d consider fair treatment. They’ll condemn people as racist if they treat someone below that baseline of fairness - that is the most egregious form of racism. However, they’ll also do favours for people (i.e. treat them above the baseline) if they are perceived to be like them, while treating everyone dissimilar at the baseline - i.e. favours for pepole like them, and fairness for everyone else. While that means no one can point to an individual case where someone was obviously treated unfairly, statistically it means that the minorities get treated worse.