Maybe you misunderstood OP's point and the English language can be confusing. It's south-the region, not south-the direction. "South of the Americas" means "the south region of the Americas" which is not "south of where the Americas end". Or like the top of your head is the upper part of your head, not your hat.
Everyone knows Venezuela is in South America. Which is not south of where the Americas are (Antarctica) or, confusingly if you're US-centric, is not in the American South either (Texas).
The problem raised above and the root of the confusion is that the US adopted "America" as their own instead of what it actually is, the name of 2 entire continents, the Americas. American South means US South just for US-centric commenters.
To the world this is like Germany naming itself Europe and then claiming Bavaria is European South, different from Southern Europe (e.g. Greece) or South of Europe (e.g. Greece of Africa, depending on how you spell or understand this expression).