I dont know the official rules but its obviously different than tournaments. And dont think its that crazy when players dont show their cards. Whenever i play live, this happens a lot and ive gotten used to it. Usually if you have the winner or a good hand, that player flips their cards over. When players dont flip their cards, it usually when they missed and dont think they have the best hand. Their either say nice hand or just muck their hand and the winner has to show the cards. When players dont show their cards and none of the players muck, I think the dealer has to step in and say flip them over.

I always show my cards when the opponent shows and most times dont show if the opponent doesnt show. But usually ill just ask what the other has and then pray i dont get slow rolled lol. I think cash games need to have the same rules that tournament poker has and you have to show when you are all in. The only variation would be if player a mucks, then player b wins and player a doesnt have to show but player b still does.