In my experience it's university access that's very heavily shaped by privilege, not high school.
High school is a sort of universal misery - pretty much everyone who might be applying for a job with us, from almost any country, would have gone to high school. Rich or poor, you had to suffer through it. Yes, you're a different person now than you were then, but it's still interesting to hear how people handled work and social dynamics. There is plenty of good science which correlates young adult behaviours with lifelong outcomes. And as one part of an interview process, it's a useful reference point that is less susceptible to circumstance than things like "which university did you go to".
We now hire much from many more countries than we used to, and it feels good to me that we're giving opportunities to work on open source to a wider audience. Sure, you can be cynical about our intent. Invent elaborate motivations for our process. Perhaps the answer is as simple as this - we want to work with people who are conscientious and care about getting open source into more hands, in an easier to use form, at the lowest cost. Now, that's not the worlds most profitable software strategy, but it feels good to me to make that the focus of a days work. Terrible, right? Crazy, right?