There's nothing self-contradictory about those things in themselves, obviously. It's the fact that there are other things in canon which, y'know, contradict the implied or express use of money which are contradictory. Thus rendering canon self-contradictory on this issue.
And by "other things" you're referring to that single
line of dialog in First Contact? There was never any consideration of there being no money during the production of TOS in the 1960's. And I can't recall ST: Enterprise discussing the subject one way or the other. Nor do I believe Voyager ever directly brought up the subject of no
During the creation of TNG, Gene Roddenberry express a vague idea of there being no money in the 24th century. But when pressed by the shows writers, he was unable to explain what he meant in even the most simplest of terms. The writers themselves lived in a society with money, whether deliberately or unintentionally, the existence of money in the 24th century worked it's way into the scripts.
If you say that there is no money whatsoever in the 22nd, 23rd, 24th centuries, you basically building that supposition on a single clear overt statement. Which flies in the face of dozens and dozens of examples of a more conventional financial system.
It not like it is a fifty fifty mix of yes money and no money examples. Your isolated evidence does not make the five series' position on money "contradictory."