What we call each other in terms of respect varies from culture to culture.  Western cultures tend to use terms like Mr., Mrs., and Ms.

Korean culture uses your last name first like Henry David Thoreau would be Thoreau Henry David.  If you have a title that is the most important thing to use with your name.  It is disrespectful to use Mr. or Mrs. 

Vietnamese culture uses the terms uncle or aunt for older generations and sister or brother for teens, twenties and people who are the same age as you. I wonder if the Vietnamese picked up the use of family terms as part of communism or if it existed prior to communism.

Although, in US culture we use a combination of titles and terms if you think of it.  We may use Mr., Mrs. or Ms. for strangers as a sign of respect.  Titles for people in positions of high authority in context of government, military, religion, healthcare, or academia such as President, Vice President, Secretary of.., Congressman, Senator, Pope, Pastor, Father, Dean, Detective, Officer, Principal, Vice Principal, Doctor, Nurse, Mayor, Sheriff, Deputy, General, Private, Lieutenant, or Governor to name a few.  

For very close friends we often adopt terms of family Aunt, Uncle, cousin, sister, or brother.  If we do not specifically utilize the term when talking to them we often will describe our relationship with them as though they are "like a brother", "like a sister", "she is like another mother", " he is like another father", "my adopted grandmother" or "adopted grandfather."  All these give the connotation of our relationship towards the individual who we are talking about.  As much as using terms like colleague, coworker, acquaintance give the connotation of the lack of personal closeness in the relationship. 

In Germany, women are trying to eliminate the term Fräulein. They feel that why should a women's marital status be included in her title when man's is not.   This sparked me to look at the origin of the word Ms. in English.  Ms. actually originated in 1951 as part of a business letter writing technique not as part of the women's movement according to www.dictionary.com    It was a polite way to avoid the is she married or not question in a letter and avoid offending someone. 

I really find it fascinating to look at what we call each other based on culture. 

Can you think of terms that other countries use that do not translate into Mr., Mrs., or Ms.?  I would be interested to see if other people have noticed any unusual or unique terms in their travels.