How do slot club cards work?

Do rewards cards encode to show if a player has won much more than he plays. Can they inhibit larger payouts until an imbalance between winning and losing totals is close to equal. Would this be legal?

[Steve Bourie]

The slot club cards do let the casino know how much money you have won and lost.

That information is used by the casinos to reward you with "comps" and/or cashback based on the amount of money are betting in the casino.

All gaming regulations require that results on gaming machines to be determined randomly and the casinos cannot do anything to alter the outcome of play based on your win/loss totals.