What does the Real Life Coast Guard do, though? I thought they broke ice floes in the shipping lanes and harassed drug dealers and that was pretty much it. I don't see any STARFLEET metaphor in that ...
I guess you can read the rest of the thread
They started off as a rescue service being merged with the anti smuggling revenue protection service and becomes part of the USN during wartime. from those three legs they have branched off into all kinds of work
The metaphor comes because while the ships are capable of adding to wartime fleets, war fighting is not the primary mission. Like Starfleet in the primary universe as opposed to Starfleet in the alternate universes.