To answer your question:
Anti-semetism is heavily tied in the popular consciousness to the atrocities of the Holocaust, hitler, and WW2. This era is forever romanticized and thus, will always have a special in America
2. Racial resentment -
since the post-civil rights era, Whites have perceived racism differently then we do. Since there are no longer the overt signs of discrimination, such as Jim crow, they think that racism is, "largely", over.
This has led to resentment for the many "affirmative action" policies, protests, and other products of race politics.
to them, our plight is just us complaining and refusing to move forward. To them, other groups, such as the jews and the Irish have ascended from their struggle.
They feel that we live in a post racial society that allows for any person of color to succeed on merit alone. Yo them, at this point, if black people can't succeed, it's because we're lazy and If black people are harassed by the police, it's because we're thugs.
So when racism is brought up on in the media, it unconsciously, triggers this resentment.
White americans roll their eyes when the racism comes up