Another thing to consider: when the class of a military vessel is mentioned today, it can indicate one of two things - the specific design of the ship, or the intended purpose of the ship. That is, if a ship is identified as Ticonderoga
class, you can tell she's built to the same specs as several other vessels of which USS Ticonderoga
was the first; if she is identified as minehunter class, you can tell she's built for minehunting. (There's a grey area unless you know the terminology, of course; you might mistake "AEGIS
class" for the first case when it's actually the second.)
However, when the class of a civilian vessel other than cruise ship is mentioned, it's virtually never the first case, and basically always the second. If you see a container ship, it's unlikely she would represent a class in the sense of being built to the specs of a pathfinding ship; she might well be unique, but what I mean is that her "lineage" would most probably be irrelevant to you. But you would
be highly interested in whether she's Panamax class, New Panamax class, Aframax class, or perhaps Malaccamax class.
Quite possibly "Antares class" could be a Star Trek universe expression for ships in the size range of Kasidy Yates' freighter, then, encompassing hundreds of distinct designs and variants as long as they share the size. Or some other attribute of relevance to Star Trek freight hauling...