I think the OP’s point is the inherent iniquity of a remuneration system which in any given month can see your income drop wildly through no fault of your own, for example due to weather cancellations, delays or aircraft maintenance issues, or even simply your rostered flight being assigned to someone else for training or operational expediency.
Highly demoralising, and roughly the equivalent of an office worker being told “oh, don’t bother coming in Tuesday or Wednesday this week, and obviously we’ll be paying you 40% less”.