Nothing does. Just assuming it's not one cent, or worse, one euro.

comparing a tile with "a factory" does not seem wise

I never considered the prominent numbers in the game as being, or needing to be, realistic.

Take the calender as a different example. The longest a massive game lasts for many players is 300-500 turns, or six to ten years on the game calendar. I've had empire-wide populations over two trillion by that time. My math skills aren't up to quickly figuring out what kind of birth rate that would entail, but I'm pretty sure is isn't "realistic," at least if you're playing as Terrans.

Absolutely. All numbers in the game be it income, building costs, research costs, ship costs, everything are merely arbitrary values that have been "tweaked" over time into a working relationship to each other that basically makes sense.

There's no relationship between anything in the game and real life, nor does there need to be. It probably would make more sense if everything was in terms of some abstract "unit" like income unit or production unit, etc. Why they chose the units of income to be billions of credits is most likely because that's a reasonable range for a plantery economy just like initial planet populations in the range of the 6B we have on this particular planet.

As far as then how a single "building" like a manufacturing center requires 3 bc of maintenance that's just the value that makes it work in context of the game. If it bothers you to think that the maintenance of a single building is so high then consider it like Willy said as a manufacturing complex covering a significant percentage of a planet.

Any game is going to have "holes" in it's logic that requires the player to have a minimal ability to suspend disbelief. It is just a game after all.

Nope. You switched browsers, installed an add-on, or finally noticed something (maybe because you make few typos).

One cool thing that could happen is to have each nation have different currency whose value corolates with their ranking among their neighbors.

PS. When someone asked about a credit being about the value of a USD and how things wouldn't cost that much, let me reming you that the year is 2227, so who knows what the USD is worth? In just over 200 years tghe USD has lost most of its value (yes I listen to grownups when they tals about buying french fries for a quarter).

In the tv series babylon 5, one race was limited in buying weapons from another, because the value of is currency dropped as a result of the war (the were losing). It is nice when tv gets economics right.

Worrying...
But It wouldn't be beyond belief the way the world in general is going.

Yeah, CaptainYar is right. It says in the manual that population is really societal participation. Also, I imagine that immigration plays a large role in pop growth, since individual aliens probably join other civilizations all the time. That would explain why growth suddenly drops when approval reaches 50%. Nobody wants to join.

As for the bc, its probably the future incarnation of something like the Yen, where everything costs in the thousands and the poorest citizen has a couple million.

First, I should say that my rhetorical question was made with full acceptance of the fact that this game has evolved from a Terran-centered to multi-species play perspective and the narrative layer is far behind the functional ones. The main reason I didn't play GC1 very long was that I found being limited to the Terran perspective, well, too limiting.

Now back to the immediate recreational argument: Just because the Thalans "needed" that tech (which I have not needed in my several Thalan TA games) does not mean they'd require *money* to get it from another civ. With tech trading on, there is a limited barter option. If we're lucky enough to see GC3 include a meaningful commodity layer as the foundation of the economic model, then the Thalans would have even more ways to get what they need without the distractions of a primitive concept such as money.

p.s. I'm re-reading Iain M. Banks' Look to Windward just now, so I'm all re-fired up about the notion that Marx and Engels' "crisis of overproduction" could eventually lead to the end of what Banks' Culture people call "the Age of Scarcity."