In real life, I'd say "vous" to older people because they were raised that way and you should show respect to them, and I would do the same to people in power (boss and such). I would not say "vous" to a colleague or someone younger, that would be weird for me. I don't like my students telling "vous" to me either because it makes me feel old! (actually, if I would call someone "Monsieur" or "Madame" then I'm likely to follow with the "vous" but if I call them buy their first name, then it's unlikely) In films, they make say "vous" all the time as it sounds a bit romantic, maybe? Or maybe the film director is old and old fashionned? It's everyone's guess.

In English, the second person subject pronoun is always "you," no matter how many people you're talking to, and regardless of whether you know them. But French has two different words for "you": tu and vous. The difference in meaning between these two words is very important. Otherwise, you may insult someone by using the wrong "you." Tu is the familiar "you," which demonstrates a certain closeness and informality. Use tu when speaking to one friend peer / colleague relative child Vous is the formal "you." It is used to show respect or maintain a certain distance or formality with someone. Use vous when speaking to someone you don't know well an older person an authority figure anyone to whom you wish to show respect Vous is also the PLURAL "you" - you have to use it when talking to more than one person, NO matter how close you are.

First of all with strangers, and not your close friends and relatives. Public dealings, and other such interactions. Non polite form is with friends an relative and children only. This is the experience in France and Switzerland, but no rules are fixed.