"they don't have to take days to process a transaction" Unlike blockchains, banks are required to check the tx validity against fraud, money laundering, sanctio

"they don't have to take days to process a transaction" Unlike blockchains, banks are required to check the tx validity against fraud, money laundering, sanction lists, terrorist financing etc, must ensure funds could be returned if a mistake was made. They could not be processed on weekend or at night, because some transactions require manual review by human workers.