Why, instead of groups of workers simply acting on the free gifts of nature, advancing streams of material resources to one another, and using a simple unit of account to track the balance of these advances of material resources and who owes what to whom, do they have to go to someone who is in possession of stockpiles of these imaginary paper claims?
Because when you allow them to hold people accountable, people forget but the records do not. People slip, make mistakes. There are unavoidable extenuating circumstances. Factors beyond their control. Even natural disasters. So your "balanced" accounting ends up with owing units to others. And since your military pillages and imprisons people in order to keep the accounting books balanced, they have to pay back their debts or suffer and die. And of course people with a shred of decency won't do that, while people without struggle mightily to "take risks" to get their grubby mitts on every inequality they can.
Soon the champions of suffering, sadists beyond measure, have all the units, and everyone else is in their debt, pressed by their own military into slavery without end.
So basically you're a dumbass for using money and rich fucks will turn it against the people every time. Just make friends, and respect territory, and don't bother balancing every f*cking transaction, especially not for tax purposes. If you can't pay back the money you owe, then we burn the books. They're not worth enslaving a single soul.