For being supposedly intelligent life forms, human beings are incredibly disorganized. Weird Worm has an intriguing article on 5 fundamental concepts that we can't hash out as a species. For example:
3. We Can't Agree What Things Are Worth
In fact, we need a lot of stuff. And not just another box of Sham-Wows to use on the boat like that stroke-faced douche on the infomercial suggested or a new 3D television to go in the john. We have a lot of basic necessities that we have to acquire if we are to survive.
The problem is that supply, demand, economics and whatever other voodoo we sprinkle into the global financial system results in a really mind-bending brew. Currently, there are about 203 countries, depending whom you ask, as well as 32 dependencies. How many currencies are there? About 182. And that doesn’t even count the confederate money your racist uncle left you in his will.
We do need money. Nobody is going to haul a dozen eggs from their coop every time they need a pack of double A’s from the trading post. And while it would be nice if the cash in your pocket didn’t have the potential to be suddenly worthless, the truth is we’re probably too stubborn about being jerks to each other for a simple, inflation free currency to exist any time soon. Plus it’s kind of bummer for the poor nations to realize that a guy pushing papers in Omaha really did make more in a day than they do in a year.
Plus, with the increased digitization of our currencies, the differences matter less for the rich nations. Most first world citizens can walk into any industrialized country, swipe some plastic and walk out with their goods and services without touching a red cent. Or silver rupee. Or brown coconut. Or whatever people are bartering with these days.