But surely when registering it onto the Oyster the clerk who's doing it would see it's valid and enter the number of it onto the system and whatever else. Thus no need to carry it around due to the railcardcard being registered under that name/number which should be easily checkable if the RPI's can be bothered to do their job properly and check with any LU/LO Station on the system.
I've never been asked for it whenever I've been checked while it's been registed on my Oyster.
This is precisely what I thought (though I now accept this viewpoint is wrong). I'm very happy to admit that I'm wrong, though I maintain my surprise at this.
We are conditioned to 'always touch in and touch out' but noone ever mentions having your railcard/priv card with you aswell.