Every US casino I've frequented in general uses the ez pay ticket system: when you cash out you get a slip of paper with a bar code and other security coded items printed on the front, the paper can be converted into cash (at the cage or or other slot cashiers) or used in another machine. Many times the machine runs out of slips or a slip misprints (or doesn't print at all).
I was in a casino in Luzern (Lucerne fr.), and they use a smartcard system, When you cash out, you place your (special) sc in a slot and the value is transfered to it, and just as with the ez pay system, you can either get cash or play on another machine. The big plus is that the machines don't have to be restocked regularly with ez pay slips.
Why did they decide to use the ez pay as opposed to smartcards in the US?