I think that a capital world would probably attract more passengers,
but not necessarily more trade.
The number of passengers depends on the number of people who ha-
ve or want to visit the planet and who can afford to do so. With both
the bureaucracy and the unique sights (e.g. museums, etc.) a capital
world usually has, this should work to increase the number of passen-
gers, I think.
Trade, on the other hand, most probably depends on the size of the
local population (food, consumer goods, etc.) and on the size of the
local industry (raw materials, etc.).
However, most real world capitals tend to have less industry than si-
milar cities, and so capital planets could also have less trade than
comparable planets, I think.
