During all history of mankind, wrongdoers were using "words spoken by the mouth" to do all kind of bad things. Yet I miss total surveillance of privately spoken

During all history of mankind, wrongdoers were using "words spoken by the mouth" to do all kind of bad things. Yet I miss total surveillance of privately spoken words. Even without total online surveillance, by the nature of computers you are leaving so many traces that full surveillance is not necessary to at least find something. And in countries without Big-Brother like surveillance, police often got good hints by searching the equipment of a real criminal. It is just not needed to include everyone. And even with encryption, you can often see who talked to who. The "something" you are talking about is the following: good old police work. You have a reason to be suspicious? Search the guy. Just as police did the last hundred years. Just do not search everyone. Police work should be hard if we still care about citizen rights.