The reason is because the TOC has no way to determine which cards can/cannot be used - this is due to the payment card industry's helpful decision to withdraw the Solo/Electron brands.
So how are customers supposed to know what sort of card they have? None of my card issuers have made it clear.
I have a prepay MasterCard (Caxton Euro card). None of the documentation mentions it may not be accepted by certain retailers because they cannot perform online authorisation. Should they do so, or should the TOCs advertise they cannot accept prepay cards on board.