Why is the RGB model not used in the printing industry?

RGB color model is convenient for monitors and TVs, because they use three filters for red, green and blue. But this model determines how much light is absorbed, which is inconvenient when printing on paper, where it is more convenient to take into account the reflected color. That is why the CMYK color model is used for printing, which is based on subtraction (which is why it is often called subtractive) from the white primary colors: cyan subtracts red from white, yellow subtracts blue from white, and Magenta – Green. Thus, if you subtract all three primary colors of the RGB model from white, then the three additional colors of the CMY model come out exactly. It should be borne in mind that the CMY (K) model contains less color than the RGB model. Therefore, it often happens that the picture bright on the screen fades when printed.
It is not for nothing that CMYK has added black color. in reality it is very difficult to get a real black color by mixing colored paints, so it is cheaper and easier to use a separate ink for black and gray colors.