I can't speak for the big cruise ships that go on the oceans, although it is true that 3rd world country people are mostly hired for the most positions on board.
However, I worked on a steamboat that cruised the Mississippi and Ohio Rivers. We only carried 437 pax, and even though w would work 10 to 12 hour days, the pay was pretty decent. I normally averaged over $500/wk, and when you add in the other benefits, plus the entertainment I got to see for nothing was all worth it. If it wasn't for the fact I missed my wife so much I would be still be there.
So, I guess it depends on who you talk to on what their own PERSONAL experiences are/were.