There are always some issues with legit casinos also and some members have claimed that also but the only thing which makes the difference is they have valid proofs in their favour and on the other side casino checks all the technical fault and resolve the issues as it could affect their market reputation among gambler causing loss.So they also want to avoid it but for those who simply loss and can't handle it and start blaming the casino they don't give any importance to them.So you are right on the part that these people can't handle loss which is why it's said bet under your limits.
That is the difference for sure, if you are a legit casino and if there is a problem then 99% of the time it is fixed before it gets out. People who face a trouble contact support, and the staff helps them and everything gets settled and without a problem and complaint. No place could work forever without ever having any customer ever complaining, that is insane and I do not think that it could ever happen.
However, a decent casino would fix the problem and solve the complaint and maybe even give something tiny extra as an apology and it would be all great. All these people are looking to get paid by the casino for shutting up, that is the biggest problem.