[euler_]

Aren't dice and coins banned because they can be sharpened into a shiv? That would explain why cards are allowed.

[an4rchy]

If that were true though, then they wouldn't confiscate any of the makeshift dice, made of paper/cardboard etc.

[VyseofArcadia]

Nah, sometimes stuff is confiscated just to make life more miserable for the inmates.