> Instant money transfer means instantly draining someone's bank account with no recourse. Checks have plenty of opportunities to stop the money, so you can write a check on a Sunday as easily as a Wednesday. Wires are more irreversible and so you can only send those when the bank is open and there's someone to double check any suspicious behavior.

We have instant 24/7 money transfer in EU/Eurozone using SEPA Instant Credit Transfer (well technically it has "up to 10 second" delay) and it hasn't really been an issue.