Risk assessment != allowing someone to steal from you. Surely the casino knows that any game can be fallible and they could take a loss from it. I guess banks know that their computer systems could have problems and they can lose money from it. But what if I noticed if I exchanged a certain amount of money between my checking and savings account a few times, it doubled my balance? And then I repeated this many times knowing that there was an error in their system?
Now the bank if I had gotten away with it and could not be detected would then chalk it up as a loss and part of the calculated risk of having computerized banking. However if they knew I did this on purpose and took their money should they chalk that up as a loss and allow me to get away with it? No they would want that money back from me and possibly have me arrested for fraud.