That seems to be how it works, true. A bigger group from the same country, same cultural background and same customs, and living mostly in contact with each other and not mingling all that much with the locals, and they just keep living the way they did in their home country, not always even realizing when they are doing something that clashes badly with the local customs. And sometimes, with some, not caring because they feel a bit too comfortable when there are so many of them that they don't feel like they'd better try to fit in.