A free market is 99 cents cheaper than the 99 cent store.
Not exactly. The "Federalist" Founders wanted a mercantilist economy. The "Anti-Federalist" Founders were the advocates of a free market.
I think you'll find that what we have now adheres to the specifications of the Federalists.
A market can be free only if it is fair and that means regulated.
Watch it . . . that kind of thinking can get one labeled as a globalist, or socialist, or some such nonsense.
The answer to the question posed in the title is "A myth."
That is simply not the case. None of the Founders that I am aware of advocated completely Free Trade. Even the greatest financial and economic thinker of the group, Alexander Hamilton, understood that tariffs were necessary to support the government.
And what could be more hilarious than pretending that there was "free" trade when most of the exports were essentially the products of stolen labor from slaves. That slavery could only be maintained through the power of the State so it was intimately involved in production long before the commodities were ready for export. The "free" part doesn't start when the ships are loaded for export but must be throughout the whole economic chain of transactions.
Nor is Rothbard's contrast of free trade and mercantilism entirely accurate. Once men live as part of a group/tribe/nation/kingdom other factors come into play outside individual relations. Hence concern for the whole society by leaders and rulers comes to overrule individual benefits.
Free Trade may be the economic maximizing goal but let us not pretend that it ever really existed or that it can exist as long as there are nation states. Perhaps it can only be achieved via World Government when borders no long exist nor governments seeking to improve their charges lives.
There is a difference between "free market" and "fair market". An unfair market is not free, and a hindered market is not fair.
The First Federal Revenue Law
On April 8, James Madison, once again a congressman from Virginia, addressed the House. He went right to the point. Congress, he said, must "remedy the evil" of "the deficiency in our Treasury." He argued that "[a] national revenue must be obtained," but not in a way "oppressive to our constituents." He then proposed that the House adopt legislation, virtually identical to the unimplemented Confederation tariff, imposing a five-percent tariff on all imports....
...A single, uniform tariff, he insisted, had two advantages. First, it could be imposed quickly, which was important because "the prospect of our harvest from the Spring importations is daily vanishing." Second, it was consistent with the principles of free trade ("commercial shackles," he said, "are generally unjust, oppressive, and impolitic")