Re: Starfleet is the U.S. Coast Guard
Royal Navy vessels intercept drug smuggling
Royal Navy protects ships
Royal Navy protects Fishery vessels
And of course the Royal Navy fights in battles/wars when called upon
Perhaps the US Navy leaves that sort of thing to the US Coast Guard, but as the Royal Navy does that it would appear that Starfleet operates in a similar fashion to the Royal Navy.
On the continent of wild endeavour in the mountains of solace and solitude there stood the citadel of the time lords, the oldest and most mighty race in the universe looking down on the galaxies below sworn never to interfere only to watch.