Our school had no weighting and no rank. Note that the CC is generally asked to rate the curriculum for each student as “most rigorous, moderately rigorous, etc., so if you are concerned about that, ask your GC if your schedule will meet your expectation on that front.
It was up to the teacher to determine if the AP or IB exam was mandatory. When it was, the reason was that they wanted the students to have a shared goal and commitment to mastery. In several subjects, they had found it difficult to manage two sets of students with different learning goals. Seemed fair enough to me!