You seem to be assuming that someone who hasn't gotten a college degree doesn't have this knowledge. I've spent a fair bit of time over the past 4 years reading hacker news. I'd say the demographic of the hacker news commentator is generally a few years out of college. At that age, I knew more about how operating systems and filesystems worked, the internals of databases, and had a bigger collection of algorithms to draw on than the average hacker news commentator does.

I'm sure there are a lot of people who get CS degrees who never programmed a computer before college, and so, for them it is like a profession that they chose, and all their knowledge comes from college. For them, it probably seems baffling that someone right out of high school might get a CS job because they wouldn't know anything, right?

This isn't the case for hackers. Hackers started hacking as soon as they were told what software (or hardware) was and that there was some mechanism that made it work.

Designers don't learn about UX in school (I don't think, maybe I'm wrong).

Part of the reason college doesn't do so well is its serving some imagined "noble" ideal of what people should learn, rather than teaching practical knowledge.