The economy doesn't follow natural law, or - in many ways both literal and figurative - any laws at all.

If you think it should, then it'll appear to violate all sorts of principles all the time. In some cases it behaves like a closed system (employment in countries), in others it's an open system (companies). Some cases money is conserved (double entry booking), in others money behaves more like a Banach-Tarski ball (think bank money multipliers).