Because most companies view the manual as an afterthought. You've already bought it. What are you going to do if the manual is bad, return it? And even then, yo

Because most companies view the manual as an afterthought. You've already bought it. What are you going to do if the manual is bad, return it? And even then, you're returning it to a third-party store - the manufacturer isn't going to care care. You bought an ShelfExpress for 50% off at Furniture Mart, can you really expect them to care? Ikea, on the other hand, prides itself on user experience. Everything is Ikea-branded, so any complaint will come back to Ikea because the buck stops there. Everything is sold internationally, and they don't want to translate it into a dozen languages, so they have to make clear assembly diagrams. Their entire brand is built around having great assembly instructions!