There's absolutely no reason for a casino to cheat - they don't need to, they already have the house edge.
For the most part, it's because they were cheating the government and skimming funds for illegal businesses and laundering money and not paying taxes on it, not cheating the players (sorta kinda....again summarizing a lot.)
Cheating means greater profit, and (unless caught) more-reliable profit.
If players think they win more at Casino B than Casino A, Casino A makes less, not more.
If Vegas were to allow casino cheating (i.e. by refusing to regulate), if Casino A is revealed to have been cheating, then a player who plays and loses at (actually) honest casino B might have doubt (unreasonable as it may be) that their losses are legitimate. They may decide to make a fuss, complain, broadcast to their social networks that their losses were due to casino cheating. Even if casino B was actually honest, casino B now needs to constantly defends its reputation for fair play. At best, this represents an ongoing cost; at worst, casino B will lose all its traffic due to rumors that spin out of control. An honest reputation is indefensible in such an environment.
The most profitable arrangement for all casinos involved is to prioritize long-term profits and cooperate with strong policing, such that Vegas as a whole (and thereby their casino individually as well) is publically perceived as offering fair odds.
Let's say I rig the slot machines so that they can win on command, and then I hire a couple of actors to come in once every two or three days to 'win' a jackpot. The odds of anyone else actually hitting a win is actually 0 - nada, nothing, zilch. But I can't leave it at zero, if people don't think they have at least a chance, they're not going to throw money at it.
With cheating, I have all the benefits of convincing people into thinking they can win, without actually loosing any money in reality.
Probably a multitude of other sneaky things you can do with an unregulated casino if someone were to put their mind to it.
[1] https://en.wikipedia.org/wiki/Trump_Entertainment_Resorts