On a separate note I have yet to come across a mullah or maulvi who made a d'ua for all of mankind and not just muslims during the traditional Friday or Eid prayers.
I dont know what kind of mosques you go to or what kind of dua you're expecting for non-Muslims but i often see the Khateeb making dua and asking Allah to guide the unbelievers and the wrongdoers, and to bring them to the Straight Path.