The hell they don't. I got cheated at Blackjack at a strip casino. I won't name it, but if you're ever cruising the 'Vegas strip and see a casino with a tower that looks like it's reaching for the stratosphere, trust me on this: you do not want to play Blackjack there.
This was the mid-'90s and I was playing early in the morning. I was winning pretty good when this old guy plopped down when the cards got good and he stayed until they went bad. I was running pretty good, and figured it was just a coincidence. Happened a second time, and it was obvious they were sending in the anchor men to use up cards. I was still running good despite that. Next, the dealer was relieved way before his session was up. I made a few small bets, and lost a good sized one to this new dealer. I picked up my chips, and he asked if I "had enough". I told the SoB that I liked all my cards off the top of the deck, thank you so very much. This new dealer was dealing seconds and wasn't nearly so good at it as some card magicians I've known and seen perform. Never went back there.
Casinos might cheat like that, but no way would they ever use a gaffed deck like the one in the videos. You're more likely to see that in some dodgy private home games. Casinos aren't going to leave material evidence of cheating lying around. You may not like how your dealer holds the deck, or how he deals the cards, but this isn't material evidence that would hold up in any court.
Not that Poker cheating doesn't happen, pretty sure it does, such as collusion. You could possibly have a corrupt dealer working with a cheat to relieve a big money player of a bundle, though it's unlikely. If caught, that would mean some serious jail time. The house makes all its money from rake or seat rent, and so has an interest in seeing that collusion isn't occurring. Keeping the games clean is in their best interest.
Finally, more rake isn't better. :tongue: