In order to repeat what was said by someone else, “sollen” and “wollen” are often used with a subjective meaning. Next to the Konjunktiv (I + II) and certain prepositions, this is the 3rd way in which you can report speech (=indirekte Rede).
Let’s take a closer look
With a subjective “sollen” or “müssen” the person that reports what has been said is not sharing his or her own opinion but simply reporting what someone else has said without taking a stand on the topic. The source of the reported speech is not relevant as it may not be known to the reporter:
If you were a journalist on a press conference where you’d certainly know the name of the minister of economy, you’d write the following:
A: Die Wirtschaftsministerin sagte auf der Pressekonferenz, die Steuer auf Zigaretten müsse erhöht werden. Diese Maßnahme habe bereits in vielen Ländern zur Senkung des Tabakkonsums beigetragen.
But if you had heard the same information on the street or in a bus from an unknown person, you’d express it like this:
B: Die Steuer auf Zigaretten soll erhöht werden. Dadurch soll der Konsum sinken. Das soll auch in anderen Ländern funktioniert haben.
It’s basically like saying: I’ve heard, … / They say… The “sollen” form of the reported speech is much more common in everyday life:
C: “Hast du schon gehört? Der Müller soll seine Frau ermordet haben!” - “Nein” - “Doch!” - “Ohh.”
This topic is covered in: C1-L19