Screws are essential, but you can probably go without a few and if one breaks you will just throw it away and get another one.
A graphics card is expensive, and the computer might still work in some core ways without it! Yet that you might try to get repaired and go through an annoying RGA process to get a new one.
Which type of worker is the screw and which one is the graphics card?
Phrased another way. All workers sell their labor, but some people are effectively capital by themselves. A factory buys a piece of capital (the machine that creates the product) and the laborer.
The hospital hires a doctor who is both the piece of capital and the laborer. It makes sense that there is a higher price tag when a person is also the the machine that makes the product.
That capitalists value people and treat them nicer when they are also basically a piece of capital makes perfect sense.