Which is why the sentence said that the evidence would be passed to the Procurator Fiscal for them to bring the prosecution.
We have had this discussion before, the key thing to bear in mind is that a credit/debit card is not a form of payment* in itself. It is a token that allows you to access funds from your credit/current account. Even in a ticket office a card payment may decline even though you have sufficient funds available.
I agree that a passenger shouldn't be expected to know the difference between online and offline cards, so I couldn't conscience the idea of penalising them for a first occurrence of the card being declined on the train. However repeatedly offering a card that they know will decline is fraud.
*Please do not mention 'legal tender'!
Perhaps for passengers in this situation it would be prudent to check the official documentation and website each time to make sure your intended method of payment is indeed valid. By actively checking before using one's preferred method of payment I fail to see how this can be regarded as fraud if the method which was promised to be accepted cannot be, especially if the method being presented is actively encouraged by the railway industry itself (it is their stipulation after all).