I agree that ATM's are a bad solution to this. The issue there though is loose coupling of third party financial networks though compared to a general need for consistency in terms of one's own financial needs.
But loose coupling between third party payment networks (say debit card purchases over Cirrus) and the bank is not really the same problem as using Cassandra at Facebook.
But loose coupling between third party payment networks (say debit card purchases over Cirrus) and the bank is not really the same problem as using Cassandra at Facebook.