These system do not work outside the justification where they are made. Domestic Tx are fast and cheap because all parties involved have agreements and the sam

These system do not work outside the justification where they are made. Domestic Tx are fast and cheap because all parties involved have agreements and the same laws etc. etc. Cheating between local banks is rather useless because there is some kind of overload (the sate/a judge) that can order stuff to be reversed. Blockchains are for when no such trust/power based system is in place. So if you send USD to Mexico for example. You exchange USD to crypto send crypto to Mexico and sell it there to get MXN. The crypto transaction is final there is no reversing, it can not be unfunded, frozen or anything. The receiver doesn't need any kind of trust relationship to the sender. Its either transacted or not and both sides can independently verify that. Its not just a real time transaction its also a instant settlement (clearing). Other way to make settlement is if you move physical cash or gold but there goes the "instant" part.