Originally Posted by
obduro
The "why have empty cabins" question has already been answered perfectly by nux and fitch upthread, not sure why people keep asking it.
I think that it reflects an expectation amongst some passengers who have not previously come across these discussions that if there is a seat in a higher cabin that would otherwise go empty, they should be entitled to be re-seated into it for some bargain price.
Which is not to criticise those who have such an expectation, because there are (shall we say) some cultural differences at work on the opposite sides of the Atlantic.