My understanding is that a lot of primarily cargo ships back then also had passenger service. At https://archive.org/details/great-whitefleet-united-fruit-co... you can read how UFC's "Great White Fleet" used ships "intended for general fruit carrying and passenger service between New York, West Indian and Central American ports."

The passenger service existed "to satisfy the tropic-hunger of the North", and the pictures show the luxury.

It's still possible to be a passenger on a modern freighter, but not at that level of luxury.

https://history.state.gov/historicaldocuments/frus1952-54Gua... page on "Abbreviations and Cryptonyms" says UFCO, UNFC, and UNIFRUIT were used for United Fruit Company. The Danish Wikipedia mentions UNIFRUIT at https://da.wikipedia.org/wiki/CIA%27s_kodeord but the English one does not.