Given the US legal drinking age, and being raised in a traditionally Ghanaian family, this is not common for us in any way shape or form. I've noticed that with this cultural and legal difference, they're trying to create a more controlled environment for alcohol consumption, especially for younger people.
In terms of the general straightforwardness of German people, it comes from their dislike of beating around the bush. This is a culture that doesn't value small talk as much and prefer people to get straight to the point when they are speaking. This bluntness can be considered harsh to those unfamiliar with it, but actually it is seen as a sort of politeness/respecfulness in the local culture.
