^ There are a couple times where Kirk used the "You've earned your paycheck this week" line. And once where he talks about the money that has been invested in training up one of the crew, I think maybe Chekov?
Although Gene talked extensively about a no-money society, these ideas didn't
really permeate Star Trek too strongly until TNG. There's ample evidence to suggest a currency based economy still thrives in Kirk's time, though also that 23rd century humans may not always thirst after money the way that their 20th century forebears do, but in realistic terms going out to explore a galaxy where many planets still operate on economies, then humans would almost by necessity need to have
some form of collateral on the galactic stock exchange, even if they do not use such things on Earth itself, otherwise we'd find ourselves at a disadvantage at certain times. Not all galactic empires are going to be willing to just trade in shiny Pobblebeads that have been freshly minted out of a Starfleet replicator or whatever-have-you.
But yeah, I'd err on the side that says, when Kirk talks about selling the cabin, he's being very literal about
selling the cabin. And he isn't to know that by Picard doesn't do that sort of thing. Of course, "Encounter At Farpoint" suggests that even the 1701-D crew have got 'accounts' to which they can charge goods, so
some kind of monetary system evidently exists even in Picard's time.
(Although it
does raise an interesting side question about Real Estate in the 24th century: who owns all of the buildings we see whenever we go to Earth? Are they owned by the government and, effectively, therefore a mass form of "public housing"? Surely in a world where money does not exist then people would not be able to have 'ownership' over something like land or property? Does Joe Sisko own his own creole kitchen, or does he simply occupy it?)
