, you are a quasi-capitalist revanchist whose weak morality and ignorance of the Communist dialectic undermines the strength of the state and the power of the worker! Your rations are cut for a week. Now get back to shoveling!
The driven people usually produce more
, often directly from nothing, which means society is not a zero-sum game. Take a look at inflation-adjusted GDP charts and you'll notice the graphs trend strongly upwards. This is a result of the simple cause and effect of "the more stuff you make, the more stuff you have. If you want to have more stuff, make more stuff," which leads directly to purposely making stuff that's in demand (higher value stuff), trading for other stuff, wholesaling, retailing, franchising, etc.
Money is way to assign simple numeric values to what would otherwise be an impenetrable diversity of different, incomparable items, and to delink a product being sold from another product being bought. (If you have an '11 Mustang and want to buy a '12 Prius, you sell the Mustang for money and use the money to buy a Prius, adjusting the amount of money by the price difference, instead of spending two years hunting the one guy who wants to trade a Prius for a Mustang.) Meanwhile in socialist utopias, there's a massive toilet paper shortage in Venezuela being blamed on "excessive demand."
Communist appeals to morality don't carry much weight, since they happily starve farmers en masse and shoot workers in the back of the head for failing to meet the production quota. Their main industry was building walls to keep workers from fleeing. And of course the universal currency in all communist countries was the US dollar, because it was the only thing there that had actual value. Yet even they knew to maintain internal domestic currencies because without a currency system, even government projects have to operate via forced appropriation or bartering.
Star Trek's lack of any monetary system is an obvious leap backwards. How can the Federation figure out what a Galaxy class starship costs? How can it assign and procure resources or make any rational decisions regarding economic inputs? Without the ability to assign financial numbers to different courses of action, all their decisions would be nearly random guesses.
"Should we source hull plating from Procyon 7 or Dadelon 5?" In our universe, we'd compare price, quality, and schedule. In their universe, they have to calculate production costs, which to them would mean calculating hundreds of thousands of hypothetical barter or trade exchanges required to shift resources, equipment, and personnel to their project instead of some other project. Unless they are given the power to commandeer equipment and order citizens about on a whim, they have to figure out, have to negotiate, what it will take to draw each worker onto the project.
Weeks of negotiation later:
"Okay, worker XB71539, the Federation will give you three original Al Yankovic CD's, a year's supply of cat food, an apartment with a north facing view, a season pass to the Red Sox games, a set of Zephram Cochran commemorative stamps, and tell your girlfriend that you're on a vital mission in Romulan space."
By the time they finish figuring out what it will take they'll have to start over with renegotiations because people and equipment don't stand idle for two years waiting for someone to make up their minds.