It's really common in school though. In my experience students always used "Sie" on the teacher and only some teachers said "Du".
What I find interesting about the German "Sie" is that it's not even derived from the second person, but from the third person plural.
In the 18th and early 19th century there was a linguistic fashion in german to address other people not only in the already existing 2nd person singular and plural, but in the 3rd person singular and plural as well to better express the social status of those addressing and being addressed. If e.g. a noble would address a peasant or servant he would use the 3rd person singular, e.g. Frederic II was known to regularly ask his male subjects "Hat Er gedient?", literally "Did he serve?", meaning "Have you served (in the army)?".
The peasant or servant was expected to address a superior in the 2nd person plural (Ihr, generally with added honorifics, e.g. "Haben Euer Gnaden wohl gespeist", i.e.: "Have Your Grace enjoyed Your meal") while they would address anyone from they own class in the old, simple 2nd person singular (Du). Aristocrats among themselves would use either the 2nd person plural (Ihr) or 3rd person plural (Sie) addressing each other while the ascendant bourgeoisie preferred the 3rd person plural to a point that even children were expected to address their parents that way and were in return also addressed that way in combination with their first names, something still common in senior high schools where teachers will address students that way, e.g.: "Nicole, würden Sie bitte zur Tafel kommen?" ("Nicole, would you please come to the blackboard?") as well as parents, especially in middle and upper class families, addressing visiting friends of their adolescent children, e.g.: "Patrick, darf ich Ihnen noch ein Stück Kuchen anbieten?" ("Patrick, may I offer you another piece of cake?").
With the ascendance of the bourgeoisie in the 19th century the 3rd person plural formal address became the standard while the 2nd person plural fell out of use just like the 3rd person singular. Thus you have a 2nd person singular informal and a 3rd person formal address since nearly 2 centuries in german.