The best evidence that people really like to have transferrable currencies is that they develop independently in just about every market in the world. For example, ancient Africans used Cowry shells. Players of the videogame Diablo 2 used a particular ring, the Stone of Jordan.
While there's certainly fraud and even systemic failure at times, it's hard not to appreciate all that liberal economics has done for our quality of life.
And they also make the strange assumption they'd be engaging in the "spot trade," which also is ahistorical. It's not like you'd come to me with shoes and I'd hand over a sack of potatoes. If we're neighbors, our relationship wouldn't be about market transactions (unless I suppose we're hostile and untrusting, so we'd better trade simultaneously so we don't rip each other off).
I think Graeber's _Debt: The First 5,000 Years_ is the most illuminating source on the subject. (http://www.amazon.com/Debt-The-First-000-Years/dp/1933633867)
Of course much of that network got wiped out in the 30s recession.
I think there may be an evolutionary factor involved, easier to survive in a group so there is an incentive not to harm those around you. Able bodies can warn of nearby danger and help fight off threats, as long as you aren't a threat to them and they aren't a thread to you you're golden. There's also the fact that most people are fairly content in society and like things to stay relatively constant. Nobody wants to risk the rest of their life by doing something dumb like even accidentally injuring someone, let alone purposefully killing someone.
Nevertheless, look at folks like Ted Bundy who had a very specific target for his murders and yet still killed dozens of people in his life.
I've learned a bit about money, and this comment strikes me as conspiracy theory having nothing to do with "how money really works".