Gershon, Indeed, there are tax implications to foreign flagging of ships, but essentially those are secondary considerations. Primary considerations are avoidance of the onerous Jones Act and the ability for more flexible crewing of vessels (ie, not represented by American labor unions). It is within the scope of the US Congress to do something about taxing foreign registry and they have done nothing other to perpetuate the Jones Act. The Jones Act is the primary reason why otherwise American vessels are foreign flagged.  All that aside, every ship, regardless of registry, pays significant port duties and fees, and that wends its way back to supporting the industry and the cities they visit.

Perhaps you didn't notice, but the article explained passengers must have $50,000 in emergency evacuation insurance to cruise through the Northwest Passage. At 1,700 passengers that's $85M of insurance coverage.