To become a cashless society, the economy needs to be documented and digitised. This takes time ,and there is already lot of people that don't want that. Mainly cause they don't want to pay taxes, or they are told banking channels are haram.
However this trend is slowly changing. More and more people are opening bank account. With online shopping becoming more popular, people are opening bank accounts. As more people open account, the quicker we can move to a cashless society. I think it's said, if 70 to 80% of society is using digital banking, then it's consider a cashless society. Currently we have 20 to 23% of the population with a bank account. Still a long way to go