7) Public education is vital to creating a common identity as American citizens
I would find this a slightly more compelling argument if it weren't made mostly by people who live in affluent communities where their fellow citizens are strongly discouraged from moving by zoning and other ordinances that bar the construction of cheap housing. You think some kid growing up in East New York, looking at the crumbling walls as an inexperienced teacher fumbles the lesson plan, thinks to himself "But at least I share a common identity with the kids in Bronxville's public school system whose cars I will someday have the privilege of parking"?
Actually, this makes me think that a lot of the opposition to vouchers is about that affluent suburbanite's need to maintain the delusion that they care about inner city public schools. Memo to suburban voucher opponents who "support public education": you're already sending your kid to private school. You're just confused because your tuition fees came bundled with granite countertops and hardwood floors.