In a district in the bay area, one of the elementary schools was given a certain special designation that allowed them to accept kids from the district by lottery. The condition of entering the lottery was as follows:
1. A parent must take a 2 hour tour of the school, tour times were between 9 am and 3 pm.
2. A parent must sign an agreement to volunteer at the school at least 3 days a year.
Number 2 was unenforceable, and many flouted it, but poorer (mostly non-white) families who actually managed to schedule the tour generally backed out upon hearing that requirement.
Diversity plummeted, the school went from 60% white to 90% white in 5 years (though the district as a whole became less white).
This lasted over a decade, and only recently was the system overturned by popular vote. Every incoming class since then has been significantly more diverse.
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The point is that those who can afford to live in the bay area and not work every weekday are the well to do. As a software engineer I can usually just tell my boss "I've got an important personal matter" and get the day off. People I know who work as janitors or barista's often get told "well, if you don't show up you're fired" for the same request.