^^ @magicsecret , I agree, and that is generally true. At our school, SL usually correlates with AP, and the IBD is extremely challenging and great prep for college.
There are schools in the international school community (abroad), that are effectively 100% IB but are also, because of the expat communities they serve, not selective. (They may be the only English language school there.) And they take kids who move to that country for just 2-3 years, so they don’t have the luxury of getting them set up. Most of them have worked out the easiest path to the IBD, and while it may not all be a cakewalk, it may look a bit different than what a US school would set up to provide its students with a rigorous, externally graded course of study. HL math, chem, may not be part of all kids’ degrees there as they often are here. Here, many schools use it as their fully integrated, most challenging curriculum, and it is hard! There, it may be a diploma that will allow students to have a high school degree that will allow them to access higher education in their own country (because a high scool degree from the us is useless in many places.) But we digress…
As for schools with lots of high scoring kids, it often suggests that they accept a certain type of kid (i.e., high SSAT is weighted heavily in admissions ), and/or that their student body does a lot of prepping. The latter may happen in school or more likely, the norm may be for the parents to pay for tutoring. It doesn’t necessarily mean that the school teaches better but it can signal whether it aligns with who your kid is and your expectations.
Personally, I would look at this not as a sign of school quality but for what it says about the community. At all of these schools, you’ll find (mostly) success stories as well as tales of (some) kids who had very bad experiences there. The latter is almost always a result of bad fit. The question to ask is – is this school better for a kid who…-- than is this school better than that one.