[grishka]

This is mostly unique to the US. Where I'm from, we don't use our SSNs as passwords, bank checks and direct debit are simply not a thing, and credit cards have two-factor authentication for online purchases.

[Semaphor]

2FA for online purchases is, at least in Germany, is not always a thing. I don't know how it's decided, but I'd say only about 50% -70% of online purchases trigger the 2fa of my bank.

[RandomLensman]

My understanding is that it is related to the fraud prevention capabilities (incidence?) of the other party and the amount.

[jeltz]

It is virtually always a thing here in Sweden. The only exception I have encountered the last like 5 years is Paypal.