It's a culture change!
Sometime over the past 30 or so years the use of "Captain" has been changed by those that see it somewhat differently to those that are older. This seems to be a sign of the times? Not one that I support. As an example, my father was a Master Mariner (A ship's Captain) and he was always addressed as Captain, even when he moved to a shore position with the same company and later as a Marine Surveyor. His ship was sunk by the Germans in WWII, and he spent 4 yrs in a POW camp in Germany. All of the correspondence that I have seen (and still have) the mail was addressed to "Captain”, and he even had "Capt" prefix in the white pages (you remember them?)
Somewhere along the line the use of the title and other similar ones has been changed by those that don't seem to respect what it really means. Of course, there is a time and place for its use and perhaps the change has come about because of, shall I say "inappropriate" use (as described in previous posts) - maybe the later generations just don't understand or have not been in the classroom when it was discussed?
When I was flying as PIC, my company always used the prefix of Captain, even on boarding passes when deadheading. It was the way it was. Nevertheless when used appropriately, it should be respected.