How much time does it take to ASK someone how they would like to be called?! I used to run a gardening business and always asked my clients. Some of them preferred Mr/Mrs/Miss, some preferred their first names and a couple actually wanted to be called by a shortened/nickname.
I don't mind if someone calls me by my first name, but I do get annoyed if they then expect me to call them by their surname & title, which Doctors and nurses tend to expect.
It could be worse though - I was in a shop recently where the person behind the counter addressed me as 'doll'.