"I don't see it, therefore it doesn't exist/isn't a problem," is probably the quintessential expression of privilege and mainstream obliviousness.
For my part, when I was younger I tended to believe that racism was a minor curiosity, the realm of backwoods hicks and fringe nutcases; but more or less gone from mainstream society. Then I started reading and listening to minority voices, to black people, hispanic people, First Nations people, and so on. And when I really paid attention to their experiences, it became much more obvious how thoroughly ingrained racism still is in mainstream American culture. The violent racism is far less common than it was in the '50s and '60s (but seems to be having a resurgence of popularity), but subtle, sneering, patronizing racism is still endemic.
I think what really clinched it for me was finally coming to terms with, and coming out as, a transgendered person. Once I did that, I became more acutely aware of how pervasive transphobia is in American culture, not just mainstream culture, but so many different subcultures and under-cultures. Constantly being the butt of jokes, being snidely acknowledged as this sort of person who is protected by certain socio-political conventions, but is not worthy of any consideration or courtesy or respect beyond the minimum mandated responsibility to pretend that such a person as myself is an equal member of a society that underneath that pretense would prefer that I did not exist.
That was an "a ha" moment, that enabled me to more easily understand what other groups endured, and made me become more skeptical regarding claims of living in a "post-racial" society, and more skeptical of the white mainstream portrayal of minority experiences.