In my South Jersey neighborhood we used the term "uncle" for adult male family friends and "auntie" for female family friends. Most neighbors had that status. That "formality" aside, things were pretty lose. Adults and kids would walk into neighbors houses unannounced and sometimes without knocking. No one locked anything or though too much of it. If it was a bad time to visit you just got told to go home and come back later, no one got upset in either direction.
Yes, I'm a little taken aback when a teenager calls me by first name. I don't see it as any kind of failing, just a change of norms. My last name is mouthful and I have never expected anyone to get it right. I'm sure if I asked my children's friends to call me Mr. M or Mr. Mike, they would without it being a problem. It's never been an issue though.
