How can we say that even a reputable gambling website won't cheat its users? we don't know because the system isn't transparent. So definitely, there are part of this that cheating really occurs sometimes on reputable or non-reputable platforms and we aren't aware of that.
If the reputable gambling website cheating the members, and the members know, they will get into the problem, and the member can chase the site with help from other people who know about the law. Yes, we don't know if the system cheats or not, but we can anticipate from the cheat by not using too big money for playing gambling.