The software on the printers is whatever you buy. Some of them run on available print languages that you can code up your own driver for should you really want to.
And for the example cited, cartridges, Epson had offered a more expensive printer with a do whatever you want ink setup. And Brother lasers have so far accepted any carts I use without complaint.
As for hard to manufacture the entire printer is a molded plastic to reduce cost (massively) and a fabrication plant made printhead. Mass manufacture only for the huge price-break.