Educate them.
Show them the world outside of their bubble. Let them interact with people different to them, expand their horizons, and enrich their personalities. A trip around the world can be useful, I think.
It’s not guaranteed. Like I said, there are well-educated racists. There are people who don’t even care about their own children, so why would you expect them to like minorities? They will never change. There is NOTHING you can do about them.
But the ones you can do something about? They could do with education.
The line doesn’t seem like a problem. It’s normal to need time to yourself. I think the people with whom this line doesn’t work well are the actual problem.