They refer to the German Democratic Republic (East Germany) that likely had different rules

Yes, I recall that the GDR exhibited some minor differences from its neighbor across the wall.

Police in Germany regularly pulls regular coach service aside to some warehouse and searches in detail everyone's posessions on them. It tends to happen close to borders but not necessarily. It happened to me close to xmas in 2008, people had to unwrap their christmas gifts... I try to fly instead since. Border police are no joke

German border police and Customs (Zoll) have a right to stop and search within 50 km of the border.