I just returned from a 10 day cruise to the Southern Caribbean two days ago. It was my first cruise in two years to the month. It was great to get back on the ocean. I had a good time. I exercised for an hour 8 of the 10 mornings. Plus I did a lot of walking in ports.
Anyway, every passenger had to present a negative COVID test result to board the ship at embarkation. That test had to be done by an approved facility like CVS or Walgreens. Not some mobile medical truck or whatever.
The test had to be done within 2 days of embarkation. So basically, I took the test on Monday with a pending flight to NYC on Tuesday, and finally ship departure on Wednesday. I took the test like at 9 a.m. and returned home. About 45 minutes later my anxiety immediately dissipated when I got a text and email from CVS with the negative result. It was then and only then that I knew for certain, I would be cruising. Had I tested positive, I would have been disappointed. However, before I booked the cruise, I knew what was required.
It's the same for ALL passengers. Why would you expect the cruise line to allow known infected passengers to board a ship? Your friends could have gone to Cancun or Cozumel without a test for their vacation.