But in this case, that's essentially what's happened. No one gets legitimate telemarketing calls anymore. They're all scam calls from some slave compound in Cambodia.

You're not wrong, but with anything digital it's as easy as moving outside the country.

With the EU being one and many at the same time, all you need is to set up shop in Bulgaria and good luck prosecuting me. I'm actually in Turkmenistan anyway. There's a reason why a lot of scam calls actually come from India.