Dave it does cut both ways but being on a water without your club card in our club is very clear. It states (bold)
you must carry your club card at all times when on club waters. Failure to do this will mean you are asked to leave the water.
And here's where discretion enters the equation, and I've heard every excuse under the sun on this subject
I give them two options
1. You can pack up and leave the water as stated in your card.
2. You can go home and get it and I'll make sure your tackle is looked after whilst you're doing it.
Here's several instances from one individual I had happen over a 6 week period.
First time I carded him, he didn't have it with him, said it's in the car.
Well I watch your tackle whilst you go and get it.....Please!
Second time he didn't have on his person it was 300 yards away with the rest of his tackle. Well are we going up to get together then, as I'm going that way!
Third time it's in his car again. "You're not going to make me go back and get it are you?" "You know the script by now.....Yes!"
I asked him why it was never with him? "Well it gets tatty if you carry it about with you." It's a card mate not some manuscript like the Magna Carta.
I also think my mate had him once without it as well. In the car again, sent him on another hike for it
Tough love may be, but after the third time he got the message, as they all do, never forgeting it again.