The goal is to go for a realistic economy.
The issue with this is that a realistic economy is not as simple as you think it is, because the real economy is reliant on debt - Buying a house, car, business etc, generally comes from loans in real life.
To combat this, we need to work out some sort of formula which will show that on average, a job will make you X amount of money in Y amount of time, compared to real life, with either X being inflated, or Y being a shorter time frame than what you'd make in real life in that time.