I've been in countries where there are major trust issues with taxis, and the very worst case I could imagine would be a service which signals to anyone watching that I'm on the street in the middle of the night, holding a smartphone which also has the ability to make irreversible transactions of a large portion of my cash holdings to an anonymous endpoint, and I'll probably get into the next vehicle to stop for me.
For a significant proportion of mooted cases where trustlessness is mooted as an advantage of blockchain technology, trustlessness doesn't actually exist and/or centralisation actually reduces problems with trust
Meanwhile, with a credit card I can buy a product from Amazon or some joe-schmoe site nobody ever heard of, and have a guarantee that Visa will back me up if the latter is a scam.
At any rate, the advantage of Bitcoin/Ether is that sending Joe Schmoe your money doesn't mean you've exposed your credit card number and billing address (likely also your physical address) to Joe Schmoe. So there's pros and cons to either system. Refunds have existed since well before credit cards were a thing. Does it require a bit more of "buyer beware" ideology? Sure, but I don't think that's any different than a cash-based society.
The move to chipped credit cards (or Apple/Android Pay) also shields my real card number and makes information unusable in case of hacking. I already hide my address by having the card statements go to a PO Box and using that as my billing address, but I know that's not a widespread practice and some institutions forbid that.
In contrast, you cant make a bank transaction without linking your identity. This is what people are talking about when they say blockchains give anonymity.
If someone cares about anonymity, that’s a huge gamble to make that the system will never have a design or implementation flaw (in the case of things like zcash which are, unlike bitcoin, attempting to provide anonymity at all), and that everyone they ever do business with is trustworthy.
That last part is guaranteed to be false. Beyond the obvious capabilities of a state-level attacker, think about why Equifax has that data in the first place. People will buy things on credit and that depends on not being anonymous – churning IDs would be like only paying cash for everything, which is known not to be viable for anyone who isn’t rich. Secondly, think about how many businesses want this data for marketing purposes: you can churn wallets all you want and it won’t help when the vendors are passing that information to companies like Acxiom, Equifax, or Google.
Monero goes further and anonymises transactions between wallets.
You don't need to assume that to see obvious benefits of a blockchain. As long as there're stupid or evil people in society central authority systems like banks can fail, rob you or be hacked. Blockchain on the other hand is more reliable.
The body of evidence to date suggests that you're much more likely to be robbed of your cryptocurrency through fraud or incompetence than you are to lose your traditional currency from a bank.
https://magoo.github.io/Blockchain-Graveyard/
Furthermore, we've already seen examples of the "authorities" behind cryptocurrency executing a rollback to modify transactions they didn't like: https://www.coindesk.com/hard-fork-ethereum-dao/
I strongly dispute the notion that blockchain is more reliable. Maybe in some ideal universe where blockchain technology is not implemented and maintained by humans.
Because the technology (right now? maybe we'll see cryptocurrencies built in hardware/os eventually) is for competent geeks, not that greedy people that store their bitcoins on exchange wallets (or use any central server). One has to ask oneself if the blockchain is more reliable for him, just as he does with other things like choosing doctors etc.
- You want to stay anonymous
- You can't trust a third party
I would argue that a functional society would not need any blockchain services as it would provide the necessary privacy defenses to do anonymous transactions and the means to enforce trust.
In the same fashion, it was argued that BTC would be useless in a correctly functioning banking ecosystem.
What these systems offer is not something impossible to do otherwise, it is a lower bound on the services a society can provide (assuming internet and computers).
If tomorrow a country has a Zimbabwe moment, people will switch to BTC. If taxis end up being to corrupt, an etherum service can take the relay.
A lot of the blockchain enthusiasts are anarchists or libertarians. They assume society is already failing or on the verge of collapse. They often fail to see that not everyone is in that mindset.