There was also an interesting game called Hardwar, a very close spiritual successor to Elite, that had a dynamic economy for many things, but strictly controlled. However, the game had rudimentary multiplayer support, and the possibility for players to manufacture some goods (or equipment) was also added. Even within the controlled economy, players could still grind economies to a halt. For a good while, the devs also released beta patches (and later stable releases), among which they experimented with a wholly dynamic economy: nothing would appear out of thin air, everything would have to be produced. In practice, small imbalances could spiral into large-scale troubles even in a single-player world, and in multiplayer things would quickly become chaotic, with wide-spread shortages.
Let me give an example. The world started with a set amount of police pilots spawned, but when any were destroyed, new NPCs wouldn't appear out of thin air, they would have needed a police ship to be produced. However, said ship was one of the best in-game, and as such, they were also expensive. Shipyards would also prioritise cheaper ships, due to how they determined they should produce from what materials they had available. Since the police forces were restricted to that one type of ship, and had troubles having them produced, over time the police force would actually go extinct - even without player intervention.
Don't get me wrong, Hardwar was a great game and quite ahead of its time. However, having seen how a dynamic economy with NPC agency would work there, and also how EVE's economy works, personally I think that dynamic economies in either Elite or Star Citizen would be a nightmare to balance well enough. And in SC's case, for ships it could be circumvented with real money anyway. (Unless you believe they really will stop selling ship packages after launch, which I personally find highly unlikely.) It's best to either go with a fully player-driven economy, or to go with a semi-dynamic one with strict controls. In a mixed environment, however, players can be smarter than the game's software, and they will find and exploit any errors in it.
Oh, and as noted by Maruun just below me for Elite, the game world's size would be too large for a fully player-driven economy.