There have been a number of passengers being caught out by Trainline, among others, following a previous purchase of a Railcard discounted ticket, by automatically applying the discount to all subsequent purchases.
GWR's app makes it really obvious that the discount is applied. It shows a highlighted "Railcard" beside every discounted fare that it displays on the journey planner output. See the screenshot below.

Then it warns the purchaser to carry the Railcard.
See below:
All fairly simple and only the really determined could actually avoid noticing the implications!
Why isn't this universal?
GWR's app makes it really obvious that the discount is applied. It shows a highlighted "Railcard" beside every discounted fare that it displays on the journey planner output. See the screenshot below.

Then it warns the purchaser to carry the Railcard.
See below:

All fairly simple and only the really determined could actually avoid noticing the implications!
Why isn't this universal?