My school barely told us students our own grades during the marking period; you basically would have to guess your grade by approximating what you got on your major assignments up to that point. I think it’s intended to help prevent grade grubbing, seeing as my college does the same thing).
We also had a system where students got their midterms (feedback-only) and term-end reports (feedback and grades) on paper about a week before they release online (to students and parents alike). This was intentional; my freshman year advisor told me it was so that we could prepare to break the news to our parents. I guess that made my school more college-like? The general vibe I got from my parents’ impression of my time in HS was that they definitely wanted to minimize parent interference.
At the same time, the attendance thing wows me. We had to get all of our absences/tardies cleared with our advisors, and even one unexcused absence in a marking period would get you a detention. More than that, and you’re looking at some pretty harsh punishments, including discussion of dismissal at 7. So maybe we had a mix of policies. My friend loves telling the story of the time the Head of House banged down his door because he slept in through all of his classes one day 
I also don’t mind postgrads. We only ever have them on the football team (the total number of non-football PGs in my year was maybe 3), they all live in senior-only housing and mostly take senior-only classes, and even in the case of the football team, the captains are elected ahead of time, so three- and four-year seniors aren’t “crowded out.” Maybe the dynamics differ elsewhere?