For the longest part of human history precious metals where commonly used as money. Then at a certain point state invented a piece of paper that you can exchange for a certain weight of gold (pound was literally a pound of gold). And then at a certain point they just said fuck it and stopped exchanging gold for paper. America for example stopped converting money to gold in 1971. Fiat currency or 'money' as we know it today, is actually a relatively new invention, and yes since the invention of fiat currency the Governments can make money from thin air. They don't use plain language as they are doing this, they usually sugar-coat it in financial terms like Quantitative easing, Inflation targeting, this bill or that bill or whatever.