Their justification will be that this is yet another loving provision from the Governing Body in their efforts to simplify things for Jehovah's people in this difficult time of the end. By lovingly providing these credit donation machines, the brothers in the accounts departments at these assemby halls can now have a lot more time to sit with their families and enjoy the program... They're so predictable...
But what they're really doing here is targeting the JW population that tends to carry little or no cash (due to the abundance of ATMs around the nation)... It's no secret that a lot less people carry significant cash in their pockets than, say, 20 years ago... It just dawned on the WT that they need to tap into the funds of those who have gone cashless because of technology...