> basically the state is really bad at running companies efficiently, and often uses them as a piggy-bank, which has been generally true forever

This is somewhat more true for Venezuela than Mexico, but in the context of the global economy the large oil reserve has put a target on the country's back, so to speak. Specifically after Venezuela nationalized their oil extraction industry and opted not to take out any more IMF loans in the early 2000s, their ability to stabilize currency was highly dependent on the oil market which since then has been often unpredictable. Combine this fact with the generally exploitative nature of the first world's relationship with Latin America ("corruption") and the middle eastern OPEC members having an outsized influence on oil production throughout the same period until today and it is not hard to see how Venezuelans came to suffer as a result.