"On the bright side, at least your friend.................with regard to taxation, social security & pension".
You have just illustrated your complete ignorance about what it is like to work in the USA (please remember that it is rather a large continent).
I will give you a modest example. When I worked out there, federal withholding tax (PAYE) was pretty universal. However, there was a 15% state tax in New York and a 10% city tax on top of that.
So, can you imagine that you are posted from NCL to LPL and then find that you have just lost 25% of your earnings? Don't you think that matters? You, it would appear, would not mind this at all.
As to "having to change bases around Europe every couple of years".
I would imagine that just about everyone in FR already does this and I doubt that they didn't know that before they joined.
For the record, I have had to work in the following countries (apart from UK) during my career:
Aden
Bahrain
USA (California, New York & Honolulu)
Bangladesh
Fiji
Belgium
"We are also exceedingly glad that you retired a couple of years ago"
I do love your use of the word "we". This is normally a Royal prerogative but I am happy to hear from you exactly which organisation has authorised you to speak on their behalf.