Why do they have sanctions and a shit economy?

Usually its because the South American country attempts some sort of socialist government that would nationalize the natural resources such as oil, which would mean Chevron and co cant drill it. See Venezuela just last week, sanctions lifted, Chevron allowed to drill. Or Chile's fascist constitution (put in place by our fascist puppet Pinochet) that we stopped them from rewriting because we didn't want them nationalizing the resources earlier this year. You are right that its no accident.