I have to assume that the poll question phrasing is obscuring quite a bit of subtlety in this instance. At least I hope so.
I've actually run into a lot of people who think this. Whenever you talk about continuing discrimination in the US, they tell you to stop playing the race card or "whining." My impression is that white people think that racism is Bull Connor with the firehoses out and burning crosses, and they are threatened by the idea that things that still happen like the disproportionate incarceration of blacks could represent a continuing racially based injustice. They mostly want to ignore and forget about the problem, to the extent that they think it's a problem at all. But I honestly think that racial discrimination, voter discrimination, and segregation are making a comeback, and nobody is talking about it as much as it deserves. The lack of bipartisan outrage over things like the impediments to voting in the South (e.g. voter ID laws, moving of poll places to hard to access locations, etc.) is stunning to me, because we just went through dismantling things like that only a half century ago. I think America is going to sleep walk itself into more and more racial tension if things keep going the way they are.