On the other hand see how double spending works in less regulated financial markets like cryptocurrency. What keeps that honor system working in financial syste

On the other hand see how double spending works in less regulated financial markets like cryptocurrency. What keeps that honor system working in financial systems is that it's backed by strong regulation and strong supervisory authorities. There are so many controls built into this that mistakes happen less often than one might think, considering the volume of non-bank transactions (think billions++, yearly). ISPs have noting of the kind. One routing mistake (or "mistake") and all of your customers' data suddenly went through China, Russia, US (you name it), for better or worse. What's worse, in a manner of speaking that data is now devalued. There's value date equivalent in the ISP's world. As a customer you have no avenues, the thing isn't even between you and any ISP you may work with. The bank will never get away with telling you "well we accidentally made this extra payment, it got routed thorough this extra bank, so now you lost 25% of the money".