Buying a Railcard .. digital

WLM21

I see there's an online ticket site offering railcards at a discount (33% off the normal price of £30) 

They refer to this card as a digital card, rather than the conventional plastic card

This is with the Trainline, but I am wondering whether this 'trainline' railcard can also be used to buy directly, say from LNER. From what I see online, buying from LNER has no extra fees to pay, but the trainline site does 

MSE_James

Yes you can use a digital railcard bought from any vendor to purchase tickets from any other vendor or in person at a ticket machine or ticket office.

There is definitely no need to pay more than the face value for any UK rail ticket.