Everyone has a culture. Culture is a complex concept. It shapes how we understand the world, ourselves, and others. Culture is like an iceberg. Others are invisible or beneath the surface.
People really do see the world in fundamentally different ways.
People behave as they do because of the things they believe in or value. People behave as they do for a reason. It's easy to misinterpret things people do in a cross-cultural setting. To keep from misinterpreting the behavior of others, you have to interpret from their point of view, not yours. Crossing cultures isn't easy.