Why do printers need ALL ink colours, even if you just want to print in black and white?

Question

My printer is asking me to replace cyan, magenta and yellow colours before it can print. I want it to just print in black and white. Its all text, no images at all (its a basic report)

Why won't it just use the black? I changed the black this morning so it's not like it's low on black.

This is the case with all printers I have had.
Why do you need ALL the inks present?

Answer 1

Any empty color will give the printer an error... any error will keep the printer from printing.

Answer 2

Sorry, but with most printers you are required to have ink in both the black and color ink cartridges in order to print in black as they work in conjunction with each other. So you will need to have the both color and black ink cartridges with ink, the same thing applies for color.

Answer 3

It probably checks the ink before it asks you whether you want colour or black.