Many societies have attempted to control how money is earned, saved and spent.
This seems to have been an attempt to create a centrally planned economy, to
create a certain psychological state in the citizen, and to keep wealth
within the national borders.
Here is the case of ancient Sparta. According to Plutarch, the semi-legendary founder of Sparta, Lycurgus, mandated that money be iron trinkets rather than the more common gold and silver of the time.
You couldn't possess gold and silver, or any other objects that conceivably could store value, And the iron trinkets themselves were treated in such a way they could not be melted down and made into other iron objects.
It was difficult to earn, spend or save other kinds of money outside the official rules. It might be done, but was difficult and also illegal.
So you're stuck doing what the system wants you to do.
And most people won't even think to notice this.