I've been in the copier/printer/fax/computer business for over 30 years. Region locking things has been going on for about that long.
It first started with designing a tab, prong or other plastic part, to prevent a cartridge from working.
Savin, some Lanier, Ricoh boxes are the same, but their cartridges won't fit.
Toshiba, some lanier, Kyocera boxes are the same, but their toner won't fit.
They use to do it with the above mentioned "break away" tabs (if you knew what to change),
but that wasn't good enough, so they put a different drive gear coupling on the rear.
But that wasn't good enough. Now a lot of them have either a CRM chip, or an RFID
chip on the back of the cartridge that gets close enough to the one in the machine to read it.
If they don't match, it won't work.
In the "olden" days of dry toner copier, they did this to prevent a person from refilling the toner
With the color copiers/printers, the particle sizes have reached such a small size, and, the temperature
melting points are becoming so small, that if you vary the toner or carrier just a very small amount,
it makes a mess and can destroy some components. The DRM on cartridges is a PITA because if
you slap a genuine new one in, and it doesn't read, it creates a service call. Sometimes, you can go
in and tell it to look for the cartridge again, but if that doesn't work, you have to reject the cartridge and
RMA it back to the company.