Public Schools force you to deal with a wide cross-section of society, especially compared to private schools (mainly mid to upper crust society) and colleges (people are there by choice, often after being part of the workforce and deciding to further themselves).

In many ways K-12 schools are run like prisons, with administrators playing god and throwing fits when challenged about their petty actions, students trapped in an environment not of their choosing, and society enforcing this structure.

I wish there were more diverse options for schooling, as I would've been much more interested in K-12 school had I been encouraged to dive into a subject, then asked to prove my knowledge, without the distraction of other subjects splitting my focus. College definitely offers much more flexibility in this regard, which has made for a much better experience.