From 1961 to 1989 the German Democratic Republic — neither democratic nor a republic in the American sense — ran a wall, dogs, and shoot-to-kill orders through Berlin. The traffic was one way: toward the West. People do not risk the wire to reach a worse life.
West Germany had markets, parties that could lose elections, and companies that had to please customers. East Germany had a plan, a secret police, and Trabants. When the wall opened, the command economy was revealed as a museum of shortages.
The American habit after 1945 was not to keep Germany. It was to let Germans govern Germans — and the ones who could choose, chose the model with prices, property, and a door they could walk through. Dictatorships fear that door. That is why they weld it shut.