Black people think in terms of we because we live in a society where the social and political structures interact with us as Black people.
White people do not think in terms of we. White people have the privilege to interact with the social and political structures of our society as individuals. You are “you,” I am “one of them.” Whites are often not directly affected by racial oppression even in their own community, so what does not affect them locally has little chance of affecting them regionally or nationally. They have no need, nor often any real desire, to think in terms of a group. They are supported by the system, and so are mostly unaffected by it.
What they are affected by are attacks on their own character. To my aunt, the suggestion that “people in The North are racist” is an attack on her as a racist. She is unable to differentiate her participation within a racist system (upwardly mobile, not racially profiled, able to move to White suburbs, etc.) from an accusation that she, individually, is a racist. Without being able to make that differentiation, White people in general decide to vigorously defend their own personal non-racism, or point out that it doesn’t exist because they don’t see it.
The result of this is an incessantly repeating argument where a Black person says “Racism still exists. It is real,” and a white person argues “You’re wrong, I’m not racist at all. I don’t even see any racism.” My aunt’s immediate response is not “that is wrong, we should do better.” No, her response is self-protection: “That’s not my fault, I didn’t do anything. You are wrong.”