Printing at printing plants and printing plants
Paints, inks, paper, toners, foils and other consumables - these are things that can not be missing from printing plants. They are ordered wholesale and also consumed in bulk. For each order, the production costs are optimized, and the appropriate technique and type of printing is selected.
Graphic designers, DTP operators and printers deal with this. They are responsible for the quality of the printout and as soon as something is wrong they are the first to be targeted by the dissatisfied boss. Their work is quite hard and I have to admit that you have to really have a fuss to do it. Work after hours, maximum focus and responsibility - definitely not work for everyone.
Wikipedia about laser printing
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image.1 The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated in order to permanently fuse the text, imagery, or both. As with digital photocopiers, laser printers employ a xerographic printing process. However, laser printing differs from analog photocopiers in that the image is produced by the direct scanning of the medium across the printer's photoreceptor. This enables laser printing to copy images more quickly than most photocopiers.
Who today does not have a printer at home. Their prices are becoming more affordable and operating costs lower. Multifunction devices offer increasingly larger scanning resolutions, less margin, larger formats, etc.
But still, such home printers are far behind the professional equipment used in professional printers. Not to mention the much larger range of techniques used, which have nothing to do with those we know from home printers. Printed roll, solvent, water, anhydrous - long to exchange. The quality of such printouts is higher, which entails the obvious higher costs of printing itself.