I think Twain here is referring to travel less as tourism, ie short vacations, but more about spending time living in different countries and getting to know people and their culture, making friends, etc.
Yeah I fully get the idea. A lot of racism is ignorance and fear. Humans are bad to take limited experiences of each other and assume that’s the whole experience. When you don’t have your own experiences with a different people, it’s easy to latch onto stories of how bad they can be and form your whole opinion around that. The best counter to that is to have good experiences instead, preferably through friendship.
But some cultures/etc make for a bad travel experience, and that will create or reinforce negative opinions. Living there longer is probably better, but the fact that racism still exists in mixing pot countries like the US proves that living together isn’t enough to make relationships good.
