> As for their equivalent version using coins, the probabilities for BBB and RBB are 1/8 and 7/8 respectively, giving RBB overwhelming odds of 7:1 in a single trick versus BBB.

That's not quite true. If starting with a full deck of cards, the odds of BBB winning are (26/52)*(25/51)*(24*50)=1/8.5. Similarly, the odds of RBB winning are 7.5/8.5, giving RBB even more overwhelming odds of 7.5:1 in a single trick versus BBB.