FACT 1: The Federation in the DS9 Era was expressly and repeatedly stated to have abandoned money in favor of the Federation's techno-socialist economy.
FACT 2: The Ferengi Alliance is a society who's hat his capitalism and a drive to obtain profit. Quark is a traditionalist in this regard.
FACT 3: Miles O'Brien and the other starfleet guys on Deep Space Nine routinely go to Quarks to buy drinks, use the Holosuites and whatnot.
Here's the sticking point: why would Quark give Miles O'Brien drinks and whatnot when he has no means to pay?
Given how unwieldy (and dangerous) it is to lug latinum from place to place, there has to be some sort of galactic banking system around (probably Ferengi-dominated) which use easily transferrable latinum-backed credits.
Look at O'Brien's life. Quark lets him drink free because, if he didn't drink, he'd never get out of the fetal position long enough to fix the station.
O'Brien actually makes repairs in Quark's bar and/or sends a technician to make repairs. Even if there wasn't a way for ''Feds drink free'' to be settled by some agreement O'Brien had billable services to counter a tab.
Darth Wedgius wrote:Look at O'Brien's life. Quark lets him drink free because, if he didn't drink, he'd never get out of the fetal position long enough to fix the station.
*golf clap*
"Believe me, there’s nothing so terrible that someone won’t support it."
— Un Lun Dun, China Mieville
Darth Wedgius wrote:Look at O'Brien's life. Quark lets him drink free because, if he didn't drink, he'd never get out of the fetal position long enough to fix the station.
At times it's represented that Quark gives Starfleet Officers free service since he's not being charged rent and he gets free maintenance work. But there are other times when it's explicitly mentioned that certain people have bar tabs; when Worf goes missing in the season 7 war arc, Quark says he wouldn't die while owing Quark money. So there's explicitly commerce happening between the Starfleet officers and Quark.
Also, Jadzia is quite clearly playing for latinum when she plays Tongo. Even if you assume that she won everything she's shown to be gambling with, she had to start with some of it in order to get into the game. So it's clear Starfleet Officers who might have to interact with trading societies are given some form of currency. For some reason it makes me think about Rome paying its legions, which meant that every fort turned into a center of commerce because that was where the money was flowing in.