Education level? You mean like not including books on Algebraic Topology in a grade school library?
That isn't what I meant, but it identifies two different perils.
Regarding replacement parts my motorcycle salesman explained to me "universal" means it doesn't fit anything.
Public school has to dumb down the syllabus enough so the dumbest kid in the class can keep up.
I know of no harm to a student struggling with arithmetic if s/he stumbles across a library book on differential calculus.
Disgusting pornography is a different story.
I know it's a slippery slope.
And I realize there may be regional variations. For example, details of how "mountain oysters" are harvested might be considered inappropriate in New "Live Free Or Die" Hampshire, but be welcome in Texas.
I'm not the one to coin the term "age appropriate". I'm not enough of a lay expert to offer constructive detail. But as a matter of principle I would not absolutize "free speech" where young impressionable children are involved. Particularly considering "public" is a euphemism for "government" school.
Am I out of line on that?
Most Republicans are incomes pooh.
It's spectacular how self-defeating they are. No telling how many Republicans got rubbed out by Republican anti-vaxers.