I like to call this the “Communist Trump Rule,” although it is one of many Amber Prisoners’ Dilemmas.
If no one of the players buys a Trump Deck, everyone has a Standard Deck. Standard Trump Deck includes all traditional Elders, and, if applicable, a Place Trump of Amber.
If one or more players buy Trump Decks, they have a Full Trump Deck, and an extra card of themselves. Full Trump Deck includes all the cards of the Standard Deck, as well as one each of the PCs as applicable. (Certain circumstances may apply. YMMV.) Other players may pick up a deck (if available; quantities are limited!) in game. Bad Stuff directly relates to number of cards from Standard Deck that are missing. Good Stuff may directly relate to deck opportunities. (“Extra place Trumps,” and the like.)