Have you ever seen the movie "Kidco"?
The movie features a bunch of kids that create a business selling horse manure from their father's farm to people as fertilizer.
The State comes after them for failing to pay taxes on the "product."
The Kid calls his father into court and asks him if he pays taxes on the horse feed when he buys it. The Father says he does.
The Kid tells the court that Taxes were paid on his product before they went into the horse, so the product coming out of the horse has already been taxed.
It works like that.
Depends on whether you are taxing the back end of the horse or the front end of the horse. It's still taxing the same product.
The kid wins his case.

An import tariff is for only imports. Can you please explain how products in the South were EVER federally taxed before the Civil War? You and others keep dancing around this historical inaccuracy.