Consider this! The content to support each ship is not equal!
Each ship only has its unique pilots once. Some ships have far more generic content than others.
Supporting two ghosts means adding one generic pilot card, base token, and dial.
It also means players who invested in two ghosts get a higher value of support than adding another small ship.
however each generic tie fighter is a few base tokens and a few generic pilot cards. 2-3 times the components required for supporting a ship that could be far more expensive.
i really think they tried their best to be as fair as possible.