Post-scarcity and not using money was conceived of by Roddenberry for The Next Generation. In TOS they were using money quite frequently. (but you can retcon this to mean Starfleet credits or money just to trade with outside species) The replicators weren't as advanced in TOS times.
In DS9 they also sort of retconned it by saying that post-scarcity applies to Earth specifically. Other planets had their own resource issues.
Post-scarcity and not using money was conceived of by Roddenberry for The Next Generation. In TOS they were using money quite frequently. (but you can retcon this to mean Starfleet credits or money just to trade with outside species) The replicators weren't as advanced in TOS times.
In DS9 they also sort of retconned it by saying that post-scarcity applies to Earth specifically. Other planets had their own resource issues.