All money is a an agreed upon means of exchange. If the Federation near unlimited resources, food, clothing, housing, an agreed upon means of exchange is reasonable.
My point is you don't need a unified means of exchange. The reason we do in real life is because governments want to tax people, and set interests, trade goods etc.
The problem with a unified means of exchange is that we don't want people exchanging certain items for other items.
Imagine if we are both given a limit of how many gasoline credits we can have a year. The government knows not everyone will reach their limit. So they count on it. They don't want people selling off their excess gasoline credits to someone else. It defeats the point of having those sorts of resource limits.
The city of rome isn't free, you can't own the whole thing, you can't own 5,000 acres of land in England, you can't get a galaxy class circle the Eifel tower for hours at a time.
Things are still controlled, and when you're trying to control what people do with things to maintain balance it seems reasonable that you want to avoid a kind of currency that could be used to subvert that system.