Jay North as Dennis "The Menace" Mitchell and Joseph Kearns as his crotchety neighbor Mr. Wilson from the old TV show Dennis the Menace. Mr. Wilson was always "Mr. Wilson" to Dennis and his pal Tommy. He was also "Mr. Wilson" to Dennis' parents Mr. and Mrs. Mitchell. A teensy bit of respect and formality for people older than you are, and people you don't know well is a nice thing and should be cultivated more than has become the sad norm.
Being presumptuous with people you have only just met or do not know that well might be common in current social interaction, but that does not necessarily mean it's a good thing.
A better practice to follow, in professional and business settings at least -- and when you have service people doing things for you around the house -- is to use the formal form of address (Mr./Ms./Mrs., etc.) until invited to do otherwise. Now, that might strike some as incredibly stuffy in 2014 when almost everyone seems to be on a first name basis right from the start, but hear me out before you change the channel.
When various service and repair people visit your home, or you take the car at the local garage for an oil change or some other kind of service for example, and money is changing hands, it's best to keep things on a slightly stiff, more formal footing than has become the norm in recent decades. Here's why.
As often as not, there will be a problem, an inconvenience, an unforeseen hiccup. Something will not be done quite like you requested and thought was understood. Or, and this one is my personal favorite, the person or people you have hired to provide some kind of repair or service on a given day and at a given time will simply not turn up. And they fail to let you know via the telephone, leaving you hanging, sometimes for several days, even after repeated calls to schedule a new date and time. We've all experienced this kind of thing at one time or another in some capacity.
So, it's much easier to navigate and resolve an issue like the kind I suggest as soon as possible when that invisible wall of formality remains in place. It's also much harder to get some service people to get on the ball and finish what he (Sorry ladies, but many are still men.) was asked to do in a timely manner when you are simply "Eddie" and "Al," or "Dave" and "Mike" to each other, behaving as though you are old buddies, who go way back, when in fact you might never have seen or spoken to Eddie before he turned up on your front step.
Not everyone is like that, of course, but too many people seem less conscientious about their work and about getting it done (and done right) when the interaction is extremely laid back from the very start. Save the relaxation for when you get home after work and wind down with a Gin&Tonic or Scotch&Water before supper. Otherwise, it's perhaps best to keep things on a slightly more formal footing.
On a closely related note, and once more bucking the current trend, children should be taught to call adults (outside of the extended family) by either Mr./Ms./Mrs./Miss So-and-so, or the appropriate professional title until invited to do otherwise. It's just the polite thing to do.