Part of the Human Comedy series
This post may contain incomplete facts
The Germans are known for their forthrightness and hospitality. Contrary to popular beliefs, they are highly mannered people. They always knock before coming in. This means to “come in” even if there’s no response or if the person inside does not want them to come in. Breaking into someone's house to conduct a misdeed is still illegal by the way.
When a German knocks on a door, he will do it like he really means it. A polite knock is not going to do it. In fact, such meekly knock could very well be perceived as an insult.