Also, the difference between a full cartridge and an empty cartridge is minimal; about 20% of the toner reservoir is filled in a new cartridge, dropping to 15% when the printer says the cartridge is empty.
At least for my laser printer you can buy two kinds of cartridge: the one that’s kind of full and the one that’s actually full.
So effectively you only get to use 25% of what has been manufactured and what you pay for? What a terrible waste.
Sounds like a lot of space wasted?
Many laser cartridges are legacy designs from before they started cheating on the amount of toner. That "extra" space was used to provide 10,000+ sheet capacity standard cartridges.
This does not pass the sniff test given if you look at a new printer cartridge it is quite compact from the old school HP Laserjet behemoths.