A good conversation of "why we should fear a cashless world" should at least mention the Book of Revelation and the Book of Daniel in The Bible. It would be negligent to omit them from discussion like this.
> And [the Beast] causes all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead, and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name.
Like most of Revelations, I think this needs to be interpreted in the context that it was written. Jews during the time of Nero saw Nero as the "the Beast". From what I understand, these "marks on the hand" were a plan by the Romans to control Jewish citizens in much the same way that modern governments try to control slum populations. I doubt the author foresaw contactless credit cards and Apple pay, though I admit that the authors of both the article and of Revelations were worried about similar consequences.
How else would you describe 21st century RFID using 1st century vocabulary? Revelation was written 2,000 years ago, and is supposed to be about things in its future, after all.
Why did it need to use 1st Century vocabulary?
I am a practising Christian, and in my heart, I suspect Jesus would say something like "don't worry about how you pay for physical stuff".
So whether it be a government sponsored currency, perhaps a world currency, to stop bad behavior and bad actors; or a public blockchain (Anarcho-capitalism). We as a society are now faced with a moral decision centered around privacy and how much of it should be entrusted to governments. Notice how the thesis of cryptocurrencies is trust-less systems, because people / governments are assumed to be nefarious by default. That is a big nuance being ignored. Ultimately (IMO) this is an issue of morality. One which benefits from reading history, analogy, literary examples or anything for that matter. We are seeing a tug of war between citizenry and governments in the financial and cryptographic realms. This is relevant.
The financial system and notions of a cashless society foster a growing anti-government sentiment. It is obvious in this and other threads; a strong pushback against government, which all relate back to the Books mentioned. It is difficult to ignore the religious or moral contexts of this topic.
Especially peculiar when Bitcoin has already established a cult following, complete with a pseudo-church which evangelizes. Not to mention it was created by a supposedly anti-government (Satoshi) person "yet to be revealed". Is playful conjecture not fair discussion? You can clearly see companies are racing to research cryptocurrencies, artificial intelligence, and what same may argue as anti-government measures.
So, I think a real world subject -- is subject -- to everything of the real world. Like the written Words of The Bible and anything else that exists for good interpretation. When 2+ Billion people identify as Christian, and they (potentially) push back against cashless societies, it will become exceptionally relevant.
These Books are relevant both historically and today.