Got a much better response to my response to their response, as below. To me it completely negates any obligation to accept card payments... something to show the Judge in the event of a prosecution anyway:
Dear Mr O'Connell
Thank you for contacting the NTA (National Transport Authority). We refer to your recent correspondence received on 17th August 2022.
Current legislation states that a passenger in a small public service vehicle shall comply with “any reasonable request made to him or her by the driver of the vehicle”, which would include seeking an alternative means of payment and the legislation also places an obligation on any passenger to “pay any fare lawfully required of him or her by the driver of the vehicle.”
It is an offence for a person not to pay the lawful fare in a small public service vehicle. If an amicable solution has not been reached between a driver and a passenger and the fare is not paid, Gardai can be contacted.
If you have any further questions please contact our Information Line on 0818 064 000.
Yours Sincerely
National Transport Authority