Currency is widely hailed as the ideal solution to the problems of barter. However, currency (at least as we know it) introduces it's own problems that are actually far worse.
First is the fact that every time you print a dollar bill (or a coin), you are using resources to do so, and the money itself is not a usable resource, which means you are reducing the amount of actually usable resources in the world. But this is a relatively small issue, not enough by itself to make currency a bad idea. So on to the real problem: the moral one.
Say your currency is little pieces of wood that are worth $50 each (you decided to do this to minimize the power of the above objection). Anyone who is driven primarily by self-interest is going to stop working on their job and just make these little
woodchip dollars, because that's a much more efficient way to make themselves rich. And if a lot of people do this, that society will no longer be able to sustain itself because you are spending so much labor making currency instead of getting meaningful work done. Your efforts to mitigate the above problem
actually made it worse, and worse by so much that it completely destroyed your society.
The solution implemented in this world is to simply have the government be the only one allowed to print money, and of course this has to be enforced with the threat of violence (because how else do you enforce anything). This does work, but it leads to the moral problem: why? What exactly is immoral about making currency for yourself? To make currency viable, we have to find a way to justify this violent enforcement of the rule that only a certain group of people is allowed to print money.
One might argue that a private individual making currency in such a situation is a sin because it makes others less wealthy, but it doesn't destroy or mess with anyone's else's property, it just indirectly devalues it. Devaluing someone else's property is not a punishable offense. If you think it is, consider a situation where only one person possesses food and only a small amount. This person's food has enormous value because it's so scarce and yet absolutely necessary. But if someone else starts farming and growing more food, the first person's food is devalued, yet clearly the farmer did not commit a punishable offense.
The other potential solution I see is to just make the currency so hard to produce for how much it's worth that no one would do it - so hard that even building a factory for it can't possibly pay off even in the very long run. But this also is a poor solution, because again you are skyrocketing the power of my first objection.
Also, bartering has this little advantage of encouraging charity. How? Well, as anti-barterers are so keen to point out, it's very difficult to be exact without currency. They think this is a flaw with bartering. But it's not necessarily. It can encourage people to make small concessions during trade. Since it is still an entirely voluntary exchange, this is not communism - or rather, it's communism without the fatal flaw of being theft.