Using sir and ma'am to address people...

[chimp3]

I use Sir and Ma'am often in my work as a nurse. Especially with the elderly. At least at first. Once someone tells me to call them by a different term I do. I am on first name basis with many of my clients. Or at least Mr. or Ms. ( I call women Ms. all the time and no one has been offended.)
I also call Dr.'s Sir or Ma'am. That is not only out of respect for their authority but also in an attempt to separate my authority from theirs. Florence Nightingale established modern nursing as an adversarial role to medical doctors. We are patient advocates not Dr. advocates. 99% of Dr.s are on the same side as the patient and we nurses do not have to push our weight around.  
The same holds true for cops. I call them Sir or Ma'am to maintain a formal distance at the same time respecting their authority and the risk they take. But when they pull me over , we are not friends. Anything I say will be used against me. Best to keep it concise and polite.