In Eastern Europe as well (especially small villages) it is acceptable to show up unexpectedly. In fact, in rural areas you can often show up at a stranger's place and expect to be invited in and given coffee or tea. Perhaps even fed.
Here in the US if someone knocks on the door the host stands in the inside doorway speaking to the visitors from across door frame. In Eastern Europe if the guest isn't going to come in the host generally steps outside the door to remove the social barrier that the door represents. It's an attitude of intimacy and hospitality that doesn't exist in the US. And I miss it.
It is the same in Taiwan as well. In fact, if someone close was in the neighborhood and did not stop by, the potential host could be offended. That is not to say that the host always welcomes the interruption, but at the same time, it is not as weird to stop by people's home unannounced than it is in America.
Commenting by HaloScan
