How Deep Does Ignorance Go?

After my divorce in 1995 I moved in with my parents. Though I was working, I was; left with some bills from the marriage, and a little extra money could come in handy. So Mom suggested that her neighbor across the street could use a little help watching his son in the afternoon. I told her I would talk to him about it, and I made an appointment to do that. In the middle of our conversation about what he needed for his son, seemingly out of nowhere, he made a disparaging remark about black people. I did not take the job, and have referred to that man as "The Grand Dragon" ever since. Yesterday afternoon I took my dog out for a short walk around our apartment complex. Usually I use her leash, but not always, this afternoon being one of the latter trips. The head of our maintenance department, a very pleasant fellow, saw us, and said that he knew I didn't let my dog run wild, and that I carry puppy-poopy-pouches,  but many don't, so the complex is planning to start reinforcing the rules about keeping dogs on leash, etc. Again, out of nowhere, came a completely bizarre negative remark about minorities. I was completely perplexed-on top of my moral offense at racial bigotry. I realize that racism is based on ignorance, but are the people who hold those ignorant views so out of touch that they really assume that all white people share their view, and therefore they can just casually drop these remarks? I don't get it. And I don't know how to respond.