> in Argentina all this info is assumed to be public

Same here. You can probably can find my address and phone numbers fairly easily from my name by a number of methods. That doesn't mean it isn't bad when an organisation spews out, or allows to be sucked out, huge numbers of people's data. With a leak like this it is practical to try scam everyone the list, searching for each person's details individually, and having to enumerate those people in the first place⁰, would mean no such attack would scale in a way to make it worthwhile bothering¹.

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[0] This seems strange when you first think it, but: the most important thing being on such a list says about you, is that you are a real existing person, whose identity could be exploited somehow. That fact is what makes any other information valuable.

[1] except for high-worth targets, which is why spear-phishing is a thing