In the UK, I get the occasional spam call ("I'm calling with regards to the recent accident that wasn't your fault..."). At its peak, I got about one such call per week. It's been months since I've had a spam call.
In France, I got zero. In the 7 years I lived there, I got exactly zero.
Every time I go to the US, I get 2-5 per day ("last chance to renew the extended warranty on your car").
As is often the case, things are bigger in the US.
I used to get occasional spam calls on my rarely-used old Polish number, but since beginning this year they somehow stopped (late effect of GDPR perhaps?)
It's not. Who told you it was?
Experience reports are still useful and interesting.
Europe is also a big pot of honey. But people speak all sorts of different languages, so you'd have to redo the scam in a bunch of different languages, which increases the effort needed to operate it.
China has way more people all speaking the same language, but relatively less wealth per person, which reduces the potential payoff. Also, I wouldn't be surprised if China has already closed off most the holes people exploit to operate these scams, because they seem less inclined than the US government to fart around about silly crap like this for literally decades on end.
Latin America has scads of people all speaking the same language, too, but they're split up among a whole bunch of different countries, which I'm guessing also makes the scam more expensive to operate at scale than it would be in the English-speaking bits of North America.
This means they'll exploit the most profitable targets almost exclusively. It doesn't have to be much more profitable, just the most.
If they were victim limited, they'd expand the pool of targets to include the most profitable N until they became resource limited again.
The problem described in https://news.ycombinator.com/item?id=22742976
Is precisely why US get so many Spam calls, and very little in many other developed countries on earth.
And judging from that, it is also no wonder why SMS passcode hijacking is much common in US as compared to many other places.
It reality it really is an US thing, much like how rest of the world have public health care ( Good or not ), and it wasn't until ObamaCare did rest of the world realise public health services is not a standard practice in the wealthiest nation on earth.
Every time this topic comes up on HN, someone asks that same question.
Then there's a bunch of responses that are lots of suppositions.
Then several people from small European countries chime in saying they've never had a spam call.
Then a bunch of Europeans from large countries show up saying they get spam calls, too, and it's not just an American thing.
"Why is this problem unique to the USA?" is pretty much a meme at this point.
Also...
You start with "Why is this problem unique to the USA?" Then follow immediately with, "I'm not saying I never get spam calls" which means it's not unique to the USA. So your first sentence is invalid.