I used to go to this restaurant for take out about once a week, and the guy at the counter would always call me by my first name multiple times per visit: "Hi Dave", "What can I get you Dave", "That'll be $7.50 Dave", "Here's your food Dave", "Have a good day, Dave".
I always paid cash, but since I was at work I had my work ID clipped to my belt loop and he saw it once and just capitalized on it. Extremely annoying.
yes, this is pretty similar to what I was getting at. It puts you in an awkward position, because if you say "I prefer that you address me as mr. or sir," you sound like a dick. You can try something like "I'm not used to customer service or business personnel addressing me by my first name," but it's still dickish.
Bottom line: it's up to an adult to determine how they prefer to be addressed, especially if it's not in a casual setting. I wouldn't address another adult by their first name in a non-casual setting unless they'd introduced themselves that way or indicated that's how they preferred to be addressed.
It's like that earlier post that brought up the "friendliness vs. politeness" thing.