No More Scarcity

There is no indication that the genetic structure of future Star Trek humanity has been drastically altered in such a way that limits are placed on wants and needs. As such, the elimination of scarcity must have resulted due to unlimited resources, likely brought about through technological advances.

Consider key land and material resources. The Star Trek future appears to have unconstrained access to productive materials. This most likely results from access to an infinite number of planets and solar systems through faster-than-light travel. The energy needed to power spaceships and other productive mechanisms also appears unconstrained. One of the key productive tools is the replicator, which evidently can produce almost any type of food or consumer product desired.

With such abundance and unrestrained satisfaction of wants needs, the trappings of real world economics is largely absent. Not only has the economics profession been suspiciously absent from all Star Trek manifestations, so too have markets and money. No one in the Star Trek universe engages it buying or selling, and hence have no need for money.

Apparently, scarcity has been solved and the wide assortment of scarcity-generated economic problems no longer exist.

Constraints, Nonetheless

Consider replicators. While material wants and needs seem to be relatively satiated through replicator technology, these devices still require energy--energy that cannot be used for other activities. While seemingly abundant, this energy does have alternative uses. Chief engineers (Scotty, or LaForge, O'Brien, et. al.) are frequently forced to divert energy from "life support systems" to the "shields" to ward off phaser blasts from alien ships. This clearly implies that the use of energy incurs an opportunity cost and further indicates that scarcity persists in the Star Trek universe.

What about the apparent lack of money? While the use of money does not surface in many aspects of the Star Trek universe, especially on the assorted starships, it does play a part in other segments of interstellar life. For example, Deep Space Nine, chronologically-speaking the third Star Trek series, contains a vibrant, money-filled economy. Most characters on this space station find the need to buy, sell, and trade commodities. The primary currency, especially for the Ferengi, is gold-pressed latnum.