are implemented with a conservativeness in approach and ruthlessness in implementation across each and every product. There have been incidents involving misuse of the payment systems / networks to defraud the participant institutions and / or their customers.
Whether the fraudsters could have been prevented from doing so can be a matter of debate, but there cannot be differing opinion that attention to security on an ongoing basis can greatly mitigate this risk. Failure to do so by one / few entities can put the entire payment system to peril.