The thing is, nothing is completely maintenance free, esp. if there's something mechanical. Make wearing parts wear, core parts robust. All my laser printers were Samsung/Xerox (hah), and their "core" is made like a tank. Only its rollers, toner and imaging/drum kits wear down, and these are already consumables.
The device keeps track the life of every of these replaceable components, and you replace them you hit these marks, because they're already worn down to hinder reliable operation (Imager dies at 9K pages, rollers at 20K pages IIRC).
You don't need to make things fail prematurely to make something profitable. First one of these printers didn't have replaceable rollers, so I had to donate it after 11 years of operation. This one is almost 8 years old IIRC, and it's still going strong. I'll be using it as long as I can find spares for it, because it's engineered "correctly", not "for profit". Meantime, its manufacturer can still profit from parts, toner and imaging units.