Designed in. You are responsible for confirming your own railcard but can’t be held responsible for confirming someone else’s.
The same at a ticket office. Theyvwill want to see both railcards before sellingbtwo discounted tickets.
But I can buy 2 tickets together online with railcards. The railcards will only be seen if their is a ticket check on the train
That might depend on the attitude of the staff at each station.
On a recent trip to Brighton for a funeral, they were quite happy to sell me two tickets, both with Senior Railcards, purely on my say-so that both passengers were entitled.
Besides, is the onus not on the passeger to ensure they have a valid ticket for the journey? If someone is using any discounted ticket (railcard, child rate etc) to which they are not entitled, it will be them who will get picked up for it on a ticket check. I am not quite sure how the booking office staff can be held resposibe, epecially given the amount of "dodgy" child tickets that are sold.