The problem isn't the technology, it's the regulatory environment. If you're the payment processor who accepts Visa/Mastercard, the customer can do chargebacks.

Now you have some scummy site that scams a million people and uses your service to accept payments. By the time the scam is uncovered, the scammer has already withdrawn the money or paid it to someone else on your service. Holding the money in escrow for long enough to prevent this will piss off legitimate sellers and some jurisdictions prohibit it. The amount per user was like a dollar but in total it's millions of dollars, so you can't just eat it. But if you don't, the users issue mass chargebacks against your service and you get banned by the credit card companies.

To make it work, transactions for small amounts have to be caveat emptor, but the existing system doesn't allow that.