I've thought about it, and have talked to some people about it - why wouldn't a casino want to let some checks and chips go if they'll never get cashed in at face value? One interesting answer I got is that the ultimate goal of the casino is for the player to use - AND LOSE - chips. In other words, it's not good enough to exchange $X for their chips - the casino wants you to exchange the bucks, then lose the chips, which is the idea of the odds of the long run.

WMD