It's software and can be manipulated.
Casino's has to win, to stay in business. They give back, just enough for you to come back for more.
Ever wondered, why there are so many cameras in a casino? If you think it's only to catch cheaters, you will be wrong. ^Evil Grin^
That's why I prefer bitcoin gambling (of course I am talking about trusted provably fair sites) to Vegas.
With a good implementation of PF, the site cannot control the bet result completely and the gamblers will easily know when the site is cheating.