It's not surprising when some people prefer convenience (such as only bringing their smartphone). Although what worries me that some places begin to only accept cashless payment.
You're right. It has become commonplace that people are starting to choose not to carry large amounts of cash. They prefer payment by online transactions, it is more simple and more secure. However, it mostly happens in city, it still can't work fine in the villages. Villagers still prefer using cash for any payment purposes. Moreover, paying online requires good internet, it is unable to do with bad internet or no internet network. So, I think we don't need to worry because it is simply impossible to have no cash payment. In certain areas cash payment may be getting rare, but there are still many areas to rely on cash payment. For example in the villages, they have no idea to use online transactions for all payment purposes.
Some government even attempt to limit usage of cash on big transaction or certain transaction type.
There is no problem if the government limit the cash, it is also still optional. I think the government didn't force us to pay with no cash. As long as it is just an optional, we shouldn't be worried so much.
