They don’t. These days most people are printing pages from their phone and printer companies don’t get deep access to iOS and Android like they do with Linux and Windows.
The printer counts the pages and sends the page count and ink levels to the mother ship and ink just shows up exactly when you need it.
> massive profits
These companies don’t have rivers of cash flowing into them. Selling and supporting printers and ink isn’t a great business. The software and hardware is expensive and hard to make. The ink is the only thing with a good margin on it and people just don’t use all that much of it.
Lots of businesses operate like this so I’m not sure why people are so upset at printer companies. When I buy a game for my PS5, I get about $2 worth of plastic and cardboard and they charge me $60 or more. Obviously it costs money to make the game and they spread that over all the copies. Well, same goes for printers and their consumables.
If you want cheap ink, buy a printer with cheap ink. They are out there and they are great. If you want to spend as little as possible on a printer, that’s out there too. You just pay more down the line for consumables.