The Wizard of Oz was a political/economic commentary

L. Frank Baum wrote "The Wonderful Wizard of Oz" as a political commentary. "Oz" was the abbreviation for "ounce" as in gold & silver. The Yellow Brick Road was gold leading to the Wizard's palace. The book version of Dorothy's slippers that she clicked together to take her home were originally silver. Baum's book was about the struggle between William Jennings Bryan and the established economic system. Bryan was an American lawyer, statesman, and politician. He was a three-time  Democratic Party nominee for President of the United States.

https://en.wikipedia.org/wiki/William_Jennings_Bryan

Cross of Gold Speech (1896)

• This is not a contest between persons. The humblest citizen in  all the land, when clad in the armor of a righteous cause, is stronger  than all the hosts of error. I come to speak to you in defence of a cause as holy as the cause of liberty—the cause of humanity.

• We object to bringing this question down to the level of persons.  The individual is but an atom; he is born, he acts, he dies; but  principles are eternal; and this has been a contest over a principle.

• There are two ideas of government. There are those who believe  that, if you will only legislate to make the well-to-do prosperous,  their prosperity will leak through on those below. The Democratic idea,  however, has been that if you legislate to make the masses prosperous,  their prosperity will find its way up through every class which rests up  on them.

• You come to us and tell us that the great cities are in favor of the  gold standard; we reply that the great cities rest upon our broad and  fertile prairies. Burn down your cities and leave our farms, and your  cities will spring up again as if by magic; but destroy our farms and  the grass will grow in the streets of every city in the country.

• If they dare to come out in the open field and defend the gold  standard as a good thing, we will fight them to the uttermost. Having  behind us the producing masses of this nation and the world, supported  by the commercial interests, the laboring interests and the toilers  everywhere, we will answer their demand for a gold standard by saying to  them: You shall not press down upon the brow of labor this crown of thorns, you shall not crucify mankind upon a cross of gold.

Bryan vowed to fight the  money changers of Wall Street and wholly supported unlimited coinage of  silver. He believed a silver backed dollar would invigorate the economy and allow the common man to thrive. He believed the gold backed dollar was a method of the elitists to control markets in their favor.

Free silver was a major political & economic issue in  late 19th century American politics. Its advocates were in favor of an  inflationary monetary policy using the "free coinage of silver" as opposed to the deflationary gold standard. Its supporters were referred to as "Silverites" of which Frank Baum was one.