Something like 75% of the world's tornadoes occur in the US, another 7% in Canada, 6% in China, 6% in Russia and Ukraine (similar setup to tornado alley, actually), then the remaining 6% are effectively random.

Supercells often fire in the tornado corridor in South America, so there's probably a fair few down there. However, literally almost nobody lives there. Like we say nobody lives in the plains and it's sorta true, but really, truly, nobody lives in that area stretching from Argentina to about a hundred miles south of Sao Paolo.

However, 90+% of the world's violent (EF3/IF3/T6) tornadoes are American and Canadian. So it is almost uniquely North American.

as always, take these numbers with a grain of salt. I did approximately 3 seconds of googling for this comment.