Probably true enough. Intelligent people realize that most prejudice (all?) is based on something superficial and easily seen - such as skin color, clothing worn, fat/ slim. There is no way that a person's visible qualities make that person either good or bad, acceptable or unacceptable as a person. And anyone with a modicum of intelligence knows that without even thinking through the thought.
I think that prejudice is a learned thing and sometimes people are prejudiced because their parents were and to think any other way doesn't occur to them. I think we would be surprised at how so many people slide through life without much deep thought.