Oh, hell, why don't *I* have the last word?!?!? Here's a man in Hue, Vietnam. A group of them were taking us to dinner at a local's home. You betcha we tipped him in dongs.
And the odds are we make more money than they do. Maybe no cars, inadequate public transpo, etc. I've been doing this for decades and, as I've written, it's a real button issue for me. I don't always have to put MYSELF first.
I've given this more thought and perhaps you're most talking about ship staff and I'm not at all. Plus having thought about this I realize that our recent travel - and not so recent - has been in Central and South America and SE Asia. I'm dropping this now. It's something I feel quite strongly about and won't be changing my mind.
Of course one would prefer any currency to none. Sorry. My point is that Americans (that seems to be who do this) don't want to go to the process of going to an ATM and getting a small amount of local currency. The cost is minimal and can't we possibly afford it more than the person 'serving' us?
Which is another topic entirely. I ask people who want to use dollars to tip, how would they like it if they got tips in pounds. They don't seem to reply to that 🙂
When we did the Norwegian coastal cruise on Hurtigruten, our ship was 100-125 and it was great. There were only two other Americans on board. A well traveled but not 'snooty' group.