This subject does get a bit complicated. The original idea was to make sure all NCL employees had their fair share for work done rather than a select few who were more obviously there and available to hand a cash tip to. It also made it easier on passengers by not having to come up with cash money at the end of a cruise. (Good Idea in my opinion) All NCL employees (my understanding here) except the " American" flagged ship are under contract to outside foreign companies and are not even paid minimum wage (American wages) much less have a paid vacation. So, from what I can see, this"resort fee" really only applies to the NCL American flagged ships because the other ship's employees are under outside contracts with few, if any, benefits.
If the $10 per day per person is going to be non negotiable, then it is only the American flagged ships who really "expect" another "tip" above and beyond the added resort fee.. Although, all would appreciate more. At least, this is my understanding of the situation. Surely, someone will correct me if I am wrong!