A game is a representation of a thing, not the thing itself. The fact that the entire planet is present doesn't preclude the artist not including superfluous bits, it just makes them stand out more. This can either be really bad (such as in Oblivion, where an entire economy is apparently run on an extremely small handful of farms) or really, really good (such as Skyrim, where one can assume that the war has done serious damage to the concept of people doing much farm work far from cities). I can't think of any games that do it, but it's entirely plausible to lampshade this concept, making it a central theme of an entire game.
Complaining about the lack of infrastructure in a game that's not about infrastructure is akin to complaining that pointalism doesn't allow for photo-realism--it misses the point. And the comparison is pretty accurate, since in a painting what you see is what you get.
A representation can nevertheless be distorted. If I were to paint the Roman Senate as consisting only of naked guys, it would still be a wrong depiction. I can easily accept that some things are there off screen, or in a painting, somewhere else, behind a wall. But if I do a painting where everyone is meeting naked in the Senate, it's the things that are on screen that are just wrong, even by virtue of the absence of some stuff. Going, basically, "no, see, the clothes are just implied, I just didn't paint them because they're not important" would be stupid, really.
If it's shown, then it damn better have all relevant details, or at the very least their absence better be meant to be symbolic of something or another.
But it's a supremely silly proposition that see, they're there, just not shown.
Ditto if I were making a movie. If I somehow made a fan-made episode of Star Trek where the bridge doesn't have a view-screen and everyone is clearly just staring at a wall, it would simply be a wrong depiction of the bridge. Unless I'm trying to make some metaphorical point by that lack of any way to see what's outside, then it's simply bad depiction of the bridge.
I could have the excuse that something is there, just not shown, if it's off-screen. E.g., I could get away with not showing the reactor controls, by just keeping it off the screen. Or I could get away with not showing a view screen if I'm never showing that wall. But if I show a solid wall without a screen in front of the captain, then it's silly to insist that, see, it's there, it's just not represented. Then it's a bad representation of that bridge, and that's that.
I don't see why games would get a free pass there.
Sure, I can think of gameplay related reasons for not making the player walk 20 miles across a capital city, or for not having a thousand acres of nothing but farms around the city. Fine.
But then the net effect is that in the name of gameplay, I AM having a dysfunctional world that's lacking some key elements. And then if those elements relate to the economy, then clearly the game has bad economics.
Again, I can see why in a choice between bad gameplay and bad economics, one would choose the latter. But nevertheless the net result is that the game, by choice, has unrealistic economics.