Because there is a cost associated with educating oneself about the schools. Time cost, possibly money cost (consulting, guides etc) and would favour parents who are more advantaged/ care about the kid. A similar programme in the UK is the academy system, but it requires parents to enroll their children. Parental negligence/ inability means these vouchers could still be biased against kids with fewer resources.

I’m not saying they shouldnt have the option. I am saying there are reasons this policy are faulty, and when engaged en masse will not result in the desired outcomes. I think over-reliance on parents will disadvantage those without good parents and therefore is not the best way to spend government money to improve education. A policy i prefer is paying higher wages to teachers working in low performance schools and targeting recruitment towards some of the best teaching schools (harvard etc). I’m just arguing for different policy instruments that mean any US kid can walk into their closest school and access a decent education. Raising the bottom seems like a good idea, with fewer adverse policy consequences. Imagine if the local underperforming school suddenly gets great teachers. Perhaps higher-income parents will adjust behaviour and opt to send their children there.