How to explain this quote from "The Survivors"?

[amp]

Also in "Firstborn" (again, TNG), Riker cashes in his stock of Federation credit vouchers in order to get Quark to give him information. Like the aforementioned bounty hunters, I don't see Quark placing any value on anything that isn't money...

I don't necessarily disagree with your larger point, but in "Firstborn" Riker actually traded in vouchers which were only good at Quark's bar.

QUARK [on viewscreen]: How could I forget the only man ever to win triple down dabo at one of my tables?
RIKER: And how could I forget that you didn't have enough latinum to cover my winnings?
QUARK [on viewscreen]: I thought I explained that my brother had misplaced the key to the safe. Besides, those vouchers I gave you are every bit as good as latinum.
RIKER: Not exactly. You can spend latinum just about anywhere. Those vouchers are only good at your bar.

 

[Imaus]

The most straight forward explaination is often the best.

Earth has a society with money by whatever name, Kevin was short on money as he was a then primarily a student and his employment was not full time. Guy was short on cash. The starving part was him fitting the role.

What is this?

'United Nations of Earth, sorry, I forgot in Star Trek it's just 'United Earth'. In StarQuest Online it was the UNE, hah.

 

[NigellaDeanna20]

An often overlooked quote from "The Survivors", for which i never found a good explanation for in line with the other episodes and movies that pretend that money doesn't exist anymore at least since the end of the 23rd century/beginning of the 24th century:

"RISHON: Kevin and I first saw each other on a ship at sea. He was a starving student with this threadbare suit and mismatched shoes. I was travelling with my parents who did not like the way that he kept hanging around. Two hours after I met him, I asked him to marry me. And he knew I was serious. I don't think that he has ever recovered from that day. "

I've always assumed that Kevin and Rishon were going from Earth To Rana IV. As for the reference to there being no moneyt in the 23rd/24th centuries, I think if I had to take an eductated guess at it, it would be that maybe it's just the Federation and Starfleet alone where money doesn't exist. Remmber, the Ferengi have gold pressed latinum as their form of currency so who knows.