In the US, I’ve heard that countries like the USSR and North Korea prevent citizens from leaving. Is this propaganda or do AES countries tend to prevent more people leaving than others?
Well, in the GDR, 20% of the population had immigrated to the west before the government started more strictly regulating emigration. Restricting who could leave was kind of a necessity at that point.
The GDR started allowing more travel to the west in the 1970s. You could visit if you were aged over 50 or had relatives in the west, and other people could also visit but they had to wait much longer and get an approval from the Stasi (most requests were approved). By 1988, millions of people legally visited West Germany each year and over 99.9% returned to the GDR.