Even if the support works perfectly in the casino, there will be people who, frustrated with failure, will accuse them of cheating. Of course, anyone who plays for a long time knows that such things happen, but remember that the gambling industry is a very large and ruthless market.
I wouldn't generalize things here. The fact that there are many gambling sites trying to scam their customer doesn't mean that the whole market is ruthless. Honest sites struggle for years to build up a good reputation, and they should not be treated as one gang with scammers.
I would not generalize either. And I add, a casino that works is one of the most profitable businesses there can be, and even more if it is online, so it has lower costs. Another thing is that it does not get much clientele, for example, and that is where some casino owners instead of thinking how to improve their business think about scamming, but a casino that makes money does not even think about it, because they are money making machines and the owners will earn much more and will have less headaches for running a honest business than trying to scam people.