How does the "roots/potatoes" incident highlight cultural bias?

The Cherokees were mistreated since the whites drove them off their lands in the 1800's. There was always this misconception of the Natives savages and beneathe the White. This was aggravated by the fact that a Congressman from Georgia called them uncivilized and that they ate roots and reptiles. At a dinner party a Cherokee leader asked the Congressman to "pass he roots" which he meant the potatoes as an act of defiance and to show that the true was in the eye of the beholder. Natives have always been denigrated and thought of as inferiors.