Folks,
In my experience the title "Captain" is quite formal and a required form of address by all other airline company staff, when addressing the "pilot in command", particularly when customers are present ---- all about
PR.
Indeed, in one pommie mob I worked for in B707 days, it was even full uniform and "Captain" even in the simulator. At one stage, with this mob, the Director of Flight Operations, appearing as a witness in an Employee Appeals Tribunal, advised the court his name was CAPTAIN David XXXXX, the retort from the bench was: "Why is the holder of a Queen's Commission working as a civilian --- or is yous name David XXXXX??". That even made the local newspaper, but he was too thick skinned to be embarrassed.
At another mob, I recall a brand new Captain, on his first trip, introducing himself, telling us that relaxed informality was the order of the day, Christian name on the flight deck, and his Christian names were "Captain" or "Sir", our choice --- he was ex-RAN and not joking.
For my money, if you were/are dependent on titles and/or uniforms for authority, you had/have already lost the game.
Tootle pip!!