I'm an European and I get zero spam calls.
I used to get a couple of cold calls per year for surveys, but I got unlisted via GDPR requests and now its down to zero.
Companies do try collecting your phone number, but then I answer NO to the obligatory "do you want the latest offers" question (in the EU, this is opt-in not opt-out). And it doesn't matter if my phone number leaks.
This is similar to my email address use. I used to get emails from recruiters, but after a couple of replies informing them that whatever profile they have is illegal, with my email address not being public, asking them to delete it, the emails stopped. I still get spam, but it's mostly fraud and US companies. Fastmail's spam filters are good enough, BTW.
My phone number works just fine, and the phone network is valuable given the better signal 2G can have, or the fact that not everyone is on the app du jour. And I find it odd when people call me on WhatsApp.
I frequently see US folks criticising GDPR, so I'm guessing this is one of those "the US mind can't comprehend" moments.