In practically all fictitious environments, creating an economy is analogous to building a boat: you can put any amount of effort into insuring a system of checks and balances towards some desired result, but ultimately without consistent intervention it will fail the test of time at some point. Pretty much every major MMO publishing game studio has struggled with this exact problem at some point during a game's lifetime. Simply put: as time progresses, the ability to control an in-game economy diminishes.
Asking for a "realistic economy" will require very strict defined parameters and an acceptance that unintended consequences are impossible to avoid. The most obvious example of this that I can think of is house location pricing. It was very apparent when we were handling auctions on LS:RP that house prices would always be subject to out of character influence which would destroy people's concept of "realism." Houses that in any other environment should be considered low-budget would be priced alongside mansions because of roleplay appeal, and even these discrepancies could be spiked or plateaued based on a faction opening or closure, and likewise who was in said factions. With a limited supply, it simply was not feasible to control it, and the ratio between full houses in "ghetto" areas and mansions between GTA:SA and GTA 5 seems significantly worse.
Houses are a useful anchor point for the value of your dollar, but managing things gets even more difficult when trying to moderate the price of drugs and weapons, particularly when trying to enforce some level of roleplay associated with either. You're essentially juggling an asset with extreme demand and low supply, and an asset with extreme supply and low demand, while trying to maintain some semblance of realism.
More or less, what I'm trying to say is don't get your hopes up. Although it'd be easy to criticize, I can assure you that any perceived problems with the economy are largely outside of anybody's control outside of development, and even then after a year or two, the state of the dollar is pretty much a gamble. It can be influenced sure, but whether you'll be sinking or swimming is really up to time.