Both Black and White culture was more civilised in the 50s than today. The statistics on crime and broken families will bear that out.
Segregation does not imply a lack of manners and civil behavior.
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!