This "news" has been out for at least 30 years. I knew of international oilfield workers who were taxed quite heavily on their foreign earnings when they returned to Canada. Sometimes they were double-taxed in their working country and resident country.

If they had set up an offshore shell company to receive employment earnings, there are ways for that company to bring money into Canada with little or no tax.

A big reason for this nefarious setup was that marginal tax rates were quite high: 70% to 90%. That incentivized wealthy earners to set up these companies. If the tax rates in those days were 40%, maybe this tax-evasion industry would not be as prolific as it is today.

As for how to fix, I say we can't until we get an international government. If Tax Havens A, B, and C capitulate on international pressure and Tax Haven D does not, not much will be accomplished. And I suspect Tax Havens A, B, & C will find ways to legally work with Tax Haven D. For example, Swiss banks were pressured to be more accountable to the international public, but Swiss banks are still doing good business. Why?