Using something like census block as a proxy for social class also can be gamed. I live in San Francisco where there is a confusing and frustrating school lotte

Using something like census block as a proxy for social class also can be gamed. I live in San Francisco where there is a confusing and frustrating school lottery that gives preference based on neighborhood of residence in an effort to help lower income families. Some wealthy friends we met at the playground moved to a (snazzy new) condo at the corner of a low-income census block for a year or two so they could get their kid an advantage in the SF kindergarten lottery, successfully getting them into their first-choice school on the other side of town. Then after the kid was enrolled for a few months, they moved to the (higher-income) neighborhood where the school is located. Being nominally in a census block with slightly higher school lottery priority is a well-understood perk of some of these fancy new condo buildings, and may even drive some amount of gentrification. (That doesn’t necessarily mean that advantaging people from lower income neighborhoods in school choice isn’t helpful, but it’s pretty hard to set up systems that actually measure what they’re intending to measure.)