> some teachers (maybe even the majority) do make carefully considered decisions
In the United States, teachers do not prescribe medications. They may make a recommendation that parents seek the guidance of a doctor, and a qualified medical professional (usually a psychiatrist) will diagnose the child, and the parent may choose to pursue medicating or not. In our case, we had regular checkup appointments with a psychiatrist where our daughter and us were present at the same time, and a later point in the session where the parents were asked to leave so the psychiatrist could speak with her privately.
> I distinctly remember overhearing a conversation where a teacher wanted to (in her words) "sedate" a problem child so that they don't disrupt the rest of the classroom.
Unless the laws have changed since then in Australia, Ritalin is a controlled substance, according to this, and it's not even guaranteed a general practitioner can prescribe it, and a psychiatrist is preferred.[1] Maybe you misheard, or maybe the teacher misunderstood what their capabilities were?
1: https://www.health.nsw.gov.au/pharmaceutical/patients/Pages/...