Stasi used people to bug on people as early as in high school - it was at least in my opinion much more nefarious than passive mass surveillance - at least it's different. I'm from the former GDR and they wreaked havoc over countless families over seemingly bullshit things. So it's difficult to compare IMHO.

But I guess it's not an impossible technical problem to train some machine learning algorithm to classify the voices and the conversation in the room and detect typical behavior patterns of a crime and be it smoking weed with friends.