It's also said to be one of the ironic long term impacts of the Jones Act (of 1920) in the US. The Jones Act among other things requires all US flagged ships at sea to be manufactured in the US in a hope to protect US manufacturing of ships, but instead in practice just became that most non-military ships just aren't officially flagged as US ships ever. For instance there's generally only one or two US flagged cruise ships in existence in a given year, they get US flagged through manufacturing loopholes (primarily constructed where other cruise ships are, but with enough "finishing touches" in the US to count as US manufactured), are smaller than the average cruise ship, and mostly only exist for Hawaiian island hopping cruises. (This is due to another quirk in the Jones Act that ships traveling directly between two US ports need to be US flagged. Most cruises can easily stop at a non-US port in between US ports, such as various Canadian, Mexican, and many Caribbean island ports, but from Hawaii the next non-US ports can be quite a bit more travel time and traveling to Tahiti and back just to see two different Hawaiian islands can be a bit much.)

Since the closure of Jeffboat in 2018 (among others), there's no non-military ship manufacturers in the US for anything even resembling cruise ship size (and even before that manufacturers like Jeffboat were mostly only making cargo barges) and the US military contractors have basically shrunk to a duopoly. Probably not the 100+ years later expectations of the Jones Act authors.