Our history probably has something to do with it, but its also an issue of the media raising awareness since the 70s. Be this out of fear-mongering to boost sales or of a sincere feeling of responsibility, it has influenced the views on privacy and surveillance of a large part of the population.

Its not just the Stasi btw., one of the canonical examples is the Nazis use of data to find and select the jews in the holocaust. This has influenced what is allowed - and especially what not - to be stored about each citizen in Germany tremendously.

Disclaimer: I'm german.