I'm not gonna generalize but I think this is more widespread in South America than you might think since pretty much all countries in the region abide by Jus Soli. Our countries are all relatively young and immigration has been such a strong driver of our culture that even defining what makes someone (e.g.) Uruguayan.
We had an absurd amount of immigration waves in Venezuela throughout the 20th Century and it'd never cross our mind to go "oh yeah this guy is Polish-Venezuelan," he'd just be Venezuelan.
I haven't been to other South American countries, so I can only speak with certainty about my country but I'm not arrogant enough to think we're the only ones like this. From watching their football broadcasts and talking about their players of less common ethnicities (e.g. Armenian) I have a feeling Argentina is similar in that way.
The school shootings and white nationalism are not because they're more open to immigrants, otherwise Canada would be a failed state at this point and Toronto would have a homicide rate that puts Central America to shame.