...I mean, if they were actually doing this despite saying that they don't—promising one product and delivering something else—I think that would be fraud, no?

And, maybe it's one thing to secretly defraud normies like us (although class action lawsuits do exist), but I don't think major enterprises or the US military would take too kindly to it.

> What is actually stopping these model companies

You can say this about any company in the world, selling anything.

It's trivially measurable, and there are people running the same benchmark on the leading models every day and measuring if they degrade. Spoiler: they don't.

But you can always say "the conspiracy goes higher", and that the companies know about these daily benchmarks and are routing them to "quality" envs.

Do you know why nobody outside the companies knows what's going on? Because they sell a black box with magic inside while steadfastly refusing to tell you if they are pushing buttons on said box while it is running.

Can you imagine how much fraud would exist in the gambling industry if the gambling commission didn't exist at all? Everytime an industry is unregulated and has high costs of entry the entities in the industry abuse their customers. The incentives are much too high for them not to.