Having experienced cashless transactions in Shanghai, I can say that it is not true that "it is still much faster to pay in cash in Singapore than to wait for machines to process the payment" (The weak pull of Singapore's cashless push, by Mr Darrell Low Wen Wei; Dec 21, 2017).
I have seen mobile phones being used to pay for purchases from vending machines and food centres in Shanghai. I have also used special cash cards to pay food hawkers there. The process is both simple and swift.
Cashless systems also eliminate the accounting work at the end of the day and a trip to the bank.
I am all for going cashless. Singapore should learn from countries like China which have progressed faster in this area.