The SAT is way more gameable than the College Board would have you believe. Most coaching is not very effective, but there is a group that is very effective. It’s almost by design that they aren’t very popular.
That said it is less gameable than most of the rest of the process. Family wealth and income are probably less gameable, but many schools are need blind.
Skeptical is putting it mildly. I'd give you better chances of having a secret proof of the Riemann Hypothesis than producing miracle educational results at scale (even if it is just on a standardized test).
They are being so vague that’s it’s impossible for us to know, but they didn’t say “at scale”. You’re certainly correct that there isn’t some secret sauce that we could just apply to everyone. But it wouldn’t surprise me if there was a service that costs (high) 5 or 6 figures per year that could substantially increase test scores.
Though I would imagine such a service would have to take place over months/years and not days/weeks, and that kind of blurs the lines of whether it even counts as test prep at that point.
That said it is less gameable than most of the rest of the process. Family wealth and income are probably less gameable, but many schools are need blind.