Well, Dream's been operating for months now without issue, so it doesn't always.
But that's not good for RCL who only just restarted. Seems they haven't got as good procedures.
I find this statement weird: "The guest who tested positive will be refunded the full amount of the cruise, according to the Straits Times. Everyone else will be refunded the value of one day on the cruise." The positive passenger would have had the same 'cruise experience' to the test point as others, and didn't apparently get it from others or onboard, so not sure why they get the extra refund. If anything, it's the other passengers who have the greatest risk of exposure to something not of their fault that I would have thought would get more compensation.