A lot of the inconsistencies between Starfleet and the U.S. Navy go away if we go with the idea that Starfleet isn't the U.S. Navy. Sure, there are lot of similarities
here and there, but Starfleet really can only be looked at as a totally different navy with its own way of doing some things. Some customs from the U.S.N. are observed, others are changed, while others are dropped entirely.