The real expansion has been coincident with fiat money and is not a result of that fiat money. Paper money is fine and certainly more convenient than carrying gold about and electronic money has largely replaced paper money in volume, at least. So long as the price level remains stable expansion will occur in a free market.In periods of inflation and deflation real expansion is retarded. Fixing money to gold is simply the easiest and surest way to maintain a stable price level, one that does not tempt politicians to fiddle with it so much and screw things up. Politicians look at the results of inflation and cry out Expansion! we've given you expansion! because of the rising prices of everything even as there is no real expansion and perhaps some contraction because of the increasingly inefficient allocation of capital that occurs in an inflation.
Inflation, in the modern world possible only with fiat money, is also a sly way to reduce wages because wages are the last price to rise in an inflation, but rise in tandem with a real expansion.
Once again the cure is worse than the disease. The price level will not remain stable under Gold. History shows chronic deflation the problem. There was always a mad search for more metal in order not to succumb to deflation. Deflation is a sure way to drop economic growth and deflation is unavoidable under the gold standard. Scarcity of money was always the cry in the past by the lower classes.
Social unrest is not something that can be just laughed off but is as certain as a democratic lie. No nation not willing to go under arms against its own people can afford the gold standard because of the negative economic forces associated with it. You think we have class warfare now you ain't seen nothing.
There is not enough gold and no scientific means of contolling its withdrawals from the money supply. It is far more arbitrary than politicians. In the past few people could afford to hoard or possess gold today we wear chucks of it on our necks. Whereas jewelry of cost was something the Nobility had today the street sweeper.
Your fear of representative government's ability to control the money supply through its elected and their instruments is another feature of your argument which is unwarranted at least for now. But the existence of the gold standard is absolutely no guarantee against tyranny.