Well, if handing over cash, credit card details or tickets it's reasonable that they would be identifable.
Also, why does Irish Rail insist on remaining in the 1960s when it comes to taking credit card details on-board. They've no terminals! My credit card details were written down on a little form and kept that way. Personally, I wasn't happy about it. Seems very sloppy.
There's no excuse for not issuing a few portable Chip and Pin terminals. Not to mention, the banks shift the liablity over to the retailer (Irish Rail) and won't offer them fraud protection if the chip is on the card and they failed to use it.