If a casino were to cheat, I doubt it would have anything to do with a faulty RNG. It would be unnecessarily awkward to change to the core RNG. Instead it's more an issue of how the RNG is used or not used. For example, a software provider could manipulate a blackjack game by programming the software to draw a random card from the deck (using RNG), then discard that card if it caused a dealer bust and draw a new random card (using RNG). A software could also make the outcome of a
BJ game like a weighted slot, instead of a deck of cards. The weighted slot would still use a fair RNG, but it wouldn't play like a deck of cards.