Western culture is difficult to bootstrap, and requires effort to maintain. In the US, civics are taught to all of your children through the education system. People have shared mythologies about freedom and duty and senses of right and wrong. Even with this, there are strong frictions between traditions.
If you resettled a city of people from Sudan or Afghanistan to a western city, those people would not suddenly become western by virtue of their new geography. In Sweden in the last twenty years, inadequately managed immigration has created a gang and gun crime culture.
I am astonished when I see westerners advocate for open borders. I think it comes from a mistaken assumption that live and let live is the default order in the world. It is not. Live and let live is a hard won cultural achievement, and needs to be tended.