From the movie "Yes Man", it was very interesting to see a scene where the main character decided to learn Korean and went to the institution where the native Korean teacher was teaching Korean language as well as cultures. Usually in Korea, the relationship between students and teachers(no matter where) are very formal, strict and firm. Students can not call teachers by their first-name. So when the teacher was called by his first-name from the movie, he was very surprised and frustrated at the same time.
Americans tend to prefer to be on a first-name basis with acquaintances. However, a title(such as Mr., Mrs., Miss or Ms.) with a last name is used when a person is addressing an employer, a teacher, a client, and older person, or a stranger in formal situations. A first-name basis is often suggested by the person with more authority ("Call me Bob").
Calling a man "Sir," or a woman "Miss" or "Ma'am" is only done in certain circumstances. Salesclerks, waiters and others who serve the public will address customers in this way. These forms are also used to get someone's attention ("Excuse me, sir. You dropped your hat.") They are traditional terms of respect but are generally used less frequently today.