Unfortunately there's just no demand for that. People have suspected they do this for years, but they get shouted down for even suggesting it.
I find it odd, because it's not just plausible, it's understandable that they would need to dynamically throttle these things or degrade people to a different model. I would be fine with that if there was transparency. I'd think a business building any type of logic on AI decision making would like to know if they are actually using Opus and not Fable. But apparently the idea that these companies don't have infinite resources is conspiratorial fear mongering to most AI boosters.