Some firms also don't even bother to give any details whatsoever, and the job offer will simply say there is a discretionary bonus, no percentage, no description at all. I actually turned down a hedge fund job because of this. I told them that in order for me to feel comfortable accepting an entirely discretionary bonus, with no baseline or agreed upon way of relating it to base salary or profits and losses, I would need a much higher base salary, and they weren't willing to negotiate about it.
The number of firms, even among extremely quant-heavy hedge funds, who award bonuses in a manner that is not overwhelmingly political is exceedingly tiny.
What this means is that the same political incentives affect even most hedge funds, and so they care far less about the mathematical rigor of what they are doing than about how to sell political stories about it. If "interpretability" sells political stories, then that's what they'll do.
Where are the hedge funds using sophisticated statistics? Maybe Renaissance. Maybe. Where else? Certainly not DE Shaw. Certainly not PDT. Certainly not G-Research. Certainly not Coatue. And on and on. When you interview at these places, and see how the sausage is made, it is eye-opening and alarming to understand just how little their business utilizes or cares about mathematics, statistical rigor, and often not even proper software design. They are just more of the same kinds of shoddy software shops cranking out ad hoc code for rapidly varying political whims, but with far better branding.
This doesn't count sell side marketing work, or slow money (insurance, mutual fund) buy side work where people get paid for Assets Under Management versus a % of the gains.