One reason why though, is that the Gestapo could rely on ordinary Germans to inform on each other. It didn't need a vast network of agents and microphones, it just needed an office to take complaints and detectives to follow up.

Unlike the Nazis, who were homegrown, the DDR was a locally administered occupation government backed by a foreign power. It was terrified of its own people and it collapsed the moment the threat of Red Army tanks rolling down the streets quit being credible.