"In other words, enable them to get credit cards or bank cards so that they can bank without high fees, so they can be mainstream members of a modern electronic society like everyone else. The bigger problem is that lower-income people are just totally detached from the modern electronic economy."

As elected officials and those campaigning against going cashless seek to ensure businesses do not exclude certain groups, one expert in consumer behavior, marketing and retail trends believes that stores are simply following consumers' lead by accepting more credit and debit cards along with mobile payments, instead of cash.

Kristen Regine, a retail and marketing professor at Johnson and Wales University in Rhode Island, US, said, "There has been a shift in consumer behavior over the past 20 years, where we are just using more plastic than we are cash.

"When people go out to a restaurant with friends, who has cash? Everyone uses a card. ... Once that happened, it opened up a whole new world for consumers."

A study by the Pew Research Center last year found that fewer dollar bills and coins were being used in the US. The study polled 10,683 adults, with 29 percent saying they made no purchases with cash during a typical week, up from 24 percent in 2015.

But a Federal Reserve report in November said, "Cash continues to be the most frequently used payment instrument, representing 30 percent of all transactions and 55 percent of transactions under $10."

The report said that while online shopping continues to grow, 77 percent of payments were made in-person, with e-commerce representing fewer than 10 percent of all retail transactions.

According to global media company Forbes, a decade ago, six of every 10 retail transactions in the US were in cash. Now three in 10 are in cash.

Regine said millennials are most likely to use digital payment platforms along with Generation Z members (those reaching adulthood in the second decade of this century).

"But Generation X (those over 40) and baby boomers are using more plastic than cash. So, while millennials lead in this and the over-60s are using more cash than the millennials, the boomers are also using plastic."