I think that's more of a way of saying that Tatooine couldn't afford to purchase and maintain an Imperial-class Star Destroyer or two for its defense fleet.
Just to confirm, Tropical Bob is right - these costs are nothing to do with 'game-play' It's simply a way for PR and I to assess the available resources of a planet/system and make sure that we get the system's defense fleet right. I/we assume that planets have to buy, steal or build their fleets. Think of this as 'behind the scenes balancing'. With over 100 planets in play we had to come up with a basic set of guidelines to populate them. Now the fleets approximately match these factors (with some interesting exceptions of course).
In fact, we have ended up with a fairly complex formula to determine the 'Planet Score' that takes into account the base financial value of a planet, land and space slots, tech level, planetary population, terrain, galactic location etc. Defense fleets are then roughly populated to the planet score, which in our system ranges from zero (one of the outer-rim / wild-space locations) to a whopping 34 for Coruscant. This score reflects a system's ability to contribute to the galactic economy and therefore it's purchasing/building/trading power.
It is not a linear scale, so there will be a huge difference in fleet strengths. My guess (Rebel/Imperial starting forces won't be done until I complete all the pirate planets) is that while some planets are ready to be taken at the GFFA outset with your humble starting forces, some worlds will still be a serious challenge in mid- or even late game.
This way you as the player get a galaxy that makes sense with itself. Poor planets with few resources don't get as big fleets as the rich industrialised ones. Without the basic underlying system it all becomes whymsical and fundamentally inaccurate.
As to adding an additional resource, personally I think it is probable not technically possible and if you do, then you open the door for all other resources to need a place, like fuel, munitions etc. Balancing would be horrendous and I would not like to guess where you got the information from. Besides, all resources eventually boil down to one common factor anyway - money.
Note - that's my opinion but you'll have to wait for PR's definitive answer on resources.
Edited by Ghostrider, 28 October 2008 - 05:17 PM.