That, and there seems to be a general disconnect between travel in general and vaccinations.
There's always been regulations for entry into certain countries and immunizations. Long before Covid. Want a visa, you may need to show an immunization record. Always been like that.
If you have cruise ships visiting foreign ports they're subject to the immunization requirements of those countries.
Any person who travels, for any reason, has to follow the requirements his destination country has.That accounts for those who may, at some point in the future, travel on short notice.
If you don't travel, and there's no vaccination mandate, don't get the vaccine. If you do travel, that's another decision, but your own country needs to be able to provide a vaccination that other countries require. International business would suffer otherwise.