Man is a social being and cannot exist without communication. And any communication begins with an appeal, and it is advisable to use a polite form in an appeal to the interlocutor. Today, a conversation with strangers begins with the words "man", "woman", "girl", "respected", "lady", "uncle" and the like, which in essence are not etiquette norms at all.
Another option to start a conversation with a stranger may be to miss the call, in this case the conversation starts with phrases such as "please (kindly)", "forgive" and the like, which by and large also does not sound very polite. And in the relatively recent past, some one hundred years ago, in order to start a conversation, one could take advantage of the respectful treatment of “sir” or “madam”.
Ma'am and monsieur
Ma'am and monsieur are, respectively, female and male forms of respectful treatment, which were widely used in pre-revolutionary Russia until the start of anti-government protests in 1917. For convenience, hereinafter, we will use the masculine form of this appeal, implying that all that is said applies equally to the feminine form of this word.
Respectfully, the address "sir" occurred while reducing the word "sovereign" by discarding the first syllable. These two terms, which are etiquette appeals, have the same meaning, and the literal interpretation of the word "sovereign" and, accordingly, "sir" is a hospitable host.
In what cases did you use this treatment?
Monsieur is an appeal that was used to emphasize respect for the interlocutor. Mostly it was applied to the intelligentsia, the upper strata of society - people of "noble blood" or noble noble origin. As a rule, people who do not belong to aristocratic families, even being financially secure (for example, merchants), did not use this appeal. However, for them in imperial Russia there were etiquette appeals - for example, the word "amiable."
This word, as well as the terms "boyar", "lady" and "young lady", was used when it was necessary to turn to someone without giving a name and surname. To refer to someone by name, as today, the words "gentleman" and "mistress" were used.
Is the appeal "sir" appropriate today?
After the revolution of 1917, all appeals applied to the intelligentsia were withdrawn from use, and they were replaced by the common words "citizen" and "comrade", which are still actively used in various fields of activity. For example, the word "comrade" is actively used in the Armed Forces. The appeal "gentleman" ("mistress") also became stable, but it is personified, it is used only to a specific person with an indication of his last name. But as for the word "sir" - this is archaism today. And if this word is used in the media or literature dedicated to the present time, then most likely the author used it to express an irony or a grin.
As you can see, historically it turned out that in Russian speech etiquette courteous appeals to strangers disappeared: the word "citizen" sounds too official, "comrade" - quickly went out of use with the termination of the USSR. And although in other countries there are polite forms of treatment, such as "sir," "Mr.," "Monsieur," "pan," in modern Russia there has not yet been invented a replacement for the obsolete "sir" and "madam".