“Are they too stupid, too corrupt?”
It’s corruption IMHO... These countries were laughed at and were called Banana Republics when I was a kid back in the 30s-40s.
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We have a culture of doing the right thing that descended from our forefathers. The industrious, religious and courageous people who came here for liberty and opportunity shaped the USA to this day.
I think the Central and South Americans never had this.