I don't think it matters much that black people may have nicely told they wouldn't be served in restaurants.
And likely a black person who attempted to go where he knew he would not be served was probably looked upon as uncivil himself. How dare he make us refuse him service instead of just staying away!
The most mannerly and civilized society during our history was the antebellum south. And its civility has been carried over to this day. Superior manners and civility are a hallmark of the people of the south to this day.
"Jim Crow" notwithstanding.
And spare me the redneck jokes.