I've had the same issue (and same solution), but it's not shady.
Brother makes reliable printers for offices. A consumer might want to print until the ink gets faded and streaky (to maximize lifespan), but for an office setting reliability is more important. You'd rather replace toner more often and have the prints always look great, than have to QC every sheet to determine if it's time to change the cartridge. Given the variable amount of ink on each printed page, Brother knows that a toner cart should last X pages 95% of the time (or whatever it is).
Brother makes reliable printers for offices. A consumer might want to print until the ink gets faded and streaky (to maximize lifespan), but for an office setting reliability is more important. You'd rather replace toner more often and have the prints always look great, than have to QC every sheet to determine if it's time to change the cartridge. Given the variable amount of ink on each printed page, Brother knows that a toner cart should last X pages 95% of the time (or whatever it is).