What they are often talking about there is countries where the official exchange rate is very different from a real world exchange rate: This happened in Argentina quite often. That led to special black market stores where people would give you local currency for dollars at better rates, and often also had some crypto support. You are then going past the legal market either way.
Possibly? Yes. But for every Argentina, there's 10 other countries where you'd loose (far more than) 40% to social security, taxes, and middleman that will handle all the paperwork for for you, particularly if we are talking about "real, productive swe jobs [that] earn enough to support not only themselves, but everyone around them as well making the place they live in a tiny bit better."
I basically have one such job, living in a stable but bottom of the table EU economy, and 40% is exactly the ballpark.
People love to rationalize tax evasion like that.
This has nothing to do with tax evasion, we're priviledged to live in countries with stable financial systems.