With that said, yes the majority of the crew are from third world nations. However, the majority of those we deal with are not dumb or stupid. Most have a higher education but are unable to find work in their own country. Most, when hired on, start at the bottom and work their way up the chain. But just like everywhere else, you treat them with dignity and respect, and they treat you the same. Also, if you tip them, they go out of thier way to help you or give you great dinner seats, etc.
Most of the officers we have met have been non-Americans. The same with the ship entertainers. You are probably correct about the cost of the cruise if the crew were all Americans but the reason you do not see many American crew members is that - in my opinion - most young Americans today do not want to work that hard. And it is hard work - long hours, day in day out.
On a Hawaiian Norwegian cruise, I did run across one American female officer in charge of the stewards. She dressed down one cleaning crew - Philippine females - in front of my wife and I. Treated them worse than dogs and in my opinion did so only because of race. We reported her. Do not know what happened to her but we did report her.
I do not feel guilty about being on a cruise. It is part of life. Like going to a fancy restaurant. You eat the great food while others serve you. That's their job. And considering the many WestPacs and Med cruise I have been on, I like these cruises better.
All cruise ships fly foreign flags. If you have a problem in international waters or in the port of call you are subject to the law of that country. Even if it is a US company like Carnival they still fly Panamanian flag so they are not subject to the Jones Act and have to pay US wages. Therefore, you are not subject to US law.
Rapes happen all the time on cruise ships. They are rarely reported because you have almost no recourse. Young women should be very careful and never open their cabin door to anyone they did not call even if they are wearing a ships uniform. This is one of the BIG secrets of the cruise industry they do not want publicized.