What this tells us is that Miss Gates is blind to her own faults and to those of the society around her. Either that or she is a major hypocrite.
In the part you are talking about, she tells the children that the difference between the US and Nazi Germany is that the US is a democracy and has no prejudices the way the Nazis are prejudiced against Jews. She is, of course, right about the first part. As for the second part, the US is not nearly as bad to its blacks as Germany is to its Jews, but it seems totally blind to stand there after the Robinson trial and say there is no prejudice.