The games are supposed to be "random" but the payout rules make the difference. In craps you get even money from bets on the pass line. But the chance you'll win such a bet is about 47% IIRC, not 50%. If you look around the craps table you'll see that the bet payouts don't match the odds of winning, and that's the vigorish for the house.

When casinos host Texas Hold'em, they simply collect a vigorish from the pot. The casino is not otherwise involved in the poker hands.