that they tried and failed is not evidence for transactions being reversible at the technical level, that's an extremely misleading interpretation on your part.

that they tried and failed is not evidence for transactions being reversible at the technical level, that's an extremely misleading interpretation on your part. we could build interbank payment systems with reversibility built in, but the matter of fact is that for the most part we haven't. payments in TARGET2 or equivalent systems are final. what guarantees reversibility is the legal system, from which crypto is definitely not exempt, contrary to what some people (including you) seem to believe. enforceability is a different question, but if you don't have a billion-dollar balance sheet like these institutions, you'll find that it's impractical for many fiat transactions too. think about it: when you sent some money in accident, who do you contact? the bank (which could simply revert the transaction if it was reversible), or the recipient (who will initiate a new transaction if they're acting in good faith)?