Here in the United States, we have gotten used to cash being the default payment method when other payment methods are not accepted or fail for one reason or another. But a few years ago, I had the pleasure of traveling to a country where cash was pretty much the only acceptable payment method. My experience there really made me appreciate the existence of mobile money transfer (MMT) services like M-Pesa. These MMTs are rapidly spreading across the developing world. Unfortunately for me, however, I had no access to an MMT in the country I visited.

In 2010, my wife was sent on a three-year assignment to her employer's Asian offices in Singapore. During one of my periodic visits, my wife and I vacationed in Myanmar, also known as Burma. Myanmar has a predominately cash-based economy.

Let me provide a little geography and history. Myanmar is bounded by Bangladesh, India, China, Laos, and Thailand. Before independence in 1948, it was ruled by the British, except during World War II, when the country was occupied by Japanese troops. At the end of the war, the country reverted to British rule. In 1962, a military coup led to nearly 50 years of military rule. In the year we visited, fewer than 600 tourists arrived at the international airport in Yangon, the busiest airport in the country.

Before our visit to Myanmar, we wired funds to a tour operator's account in Thailand to pay for the services of a driver, a guide, and some of our lodging. We estimated that we would need about $3,000 for the rest of our travel expenses during our three-week visit. At the time of our visit, Myanmar was under stringent trade sanctions due to the repressive military regime, so no international payment networks operated in the country. Consequently, the coin-of-realm for international tourists was U.S. hundred-dollar bills that could be exchanged for kyats, the local currency.

What we didn't understand is that the money exchangers required U.S. bills of the 1996 series or later with no folds, tears, markings, or stains of any sort. Yikes, we are essentially talking about uncirculated, brand-new bills. Since no international ATMs operated in the country, our first visit was to a local bank. The teller agreed to exchange only $500 after scrutinizing in microscopic detail (like a paleontologist examining a fossil) for 15 minutes our thirty $100 bills. This would cover less than our first week of expenses. We had thousands of dollars burning a hole in our pocket and no place to spend it. We were hard up.

We were getting anxious after several failed attempts at other bank branches, so our guide suggested using an unofficial currency marketer to see if we could exchange more bills. We walked a serpentine route to an untouristed, possibly unsafe area of town. Our guide took us to a money exchanger who grudgingly exchanged an additional $500. Even with further economizing, we estimated we were still short in funds for the last week of our trip. Success arrived when we met fellow travelers with excess funds they were willing to exchange.

I have wondered to this day why the reluctance to accept less-than-pristine bills. Obviously, one concern is the possible counterfeiting of $100 U.S. notes by the government of North Korea, according to some press accounts.

But whatever the reason, it left us spending $1,000 less than we anticipated. If we had had access to an MMT, we presumably would have been able to more freely purchase goods and service without wondering whether our cash would be accepted—though it should be noted that we may still have had problems with the initial cash load at an MMT money transfer agent.

Stepping back, the lessons we learned include the various risks associated with a cash economy, such as counterfeiting and, on a personal level, the disappointment of a diminished vacation due to the time and anguish spent in exchanging money. As I said in the beginning, I can appreciate firsthand the real advantages of moving away from cash to a low-cost, widely accepted mobile money transfer service. In Kenya, for example, M-Pesa reported in 2015 a 22.8 percent growth in revenue and 13.86 million active customers out of a population of 45 million. Meanwhile, next time I go to Myanmar, I'll know what to bring.

By Steven Cordray, payments risk expert in the Retail Payments Risk Forum at the Atlanta Fed