Yes, a cashless society could work. Our money-based system fails in so many ways. It keeps people from pursuing their true dreams, instead giving up their goals in exchange for a well-paying but unsatisfying job. It keeps people poor while making the rich richer. So it's failed us. It's the ultimate multi-level pyramid scheme, where those at the top do great and those at the bottom fail. So maybe a cashless system will work better. Let them try it and the rest of us can learn from it.
Other than potential job loss for people working as cashier, big companies could potentially use customer spending data to take a decisive advantage over small businesses. Train ticketing jobs in some places already eliminated by cards. There is no breakthrough in changing cash to cashless. There is a big possibility that the government/ hackers could take the money by force if they want to, data became corrupt / problems in the cloud erases data. Also cashless society would eliminate fears of shopping online since it becomes the norm, lots of jobs could potentially lost and the society will be getting more capitalist by day.
No, South Korea should hold onto the option of paying cash. Paying with cash is a simple and time-honored method of settling debts and obtaining good and services. If the country were to go cashless, it would be to the disadvantage of many low income workers and people living in poverty.
A cashless society has nothing to bank it's currency on. Not only that, but there are transactions that can only be made using cash. This is a bad idea that will result in the devaluation of Japanese currency and it will have devastating effects for their economy. It will also make thing more expensive.
No, South Korea's plan for a cashless society is not a good idea. It makes the country reliant on electronic devices which are unreliable and more easily hacked. It also will result in a greater gap between the wealthy and the poor due to lack of access to electronic devices.