The Stasi existed for 40 years. It collected between 900 million and a billion pages of data. The NSA does that every two days now.
Just for perspective. The Stasi were pikers compared to modern USA intel agencies. We don’t like t think it, but we like in the most intrusive and invasive government ever known to mankind. The Stasi only dreamed about the kind of info the NSA collects on all Americans.
The Stasi needed and got the cooperation of neighbors, relatives, etc to get a fraction of the information which our agencies get freely with our cooperation.