> Every “charter” school that actually makes a profit is simply passing on the subsidies to their owners: they get to charge both the government and parents to provide the same service.

No, they don't. Charter schools operate as non-default schools within the public school system, they don't get to charge parents at all.

> Here’s an idea: let charter schools make a profit by “being efficient”: they get exactly the same amount of money as a public school

That would be an increase, charter schools typically only get a reduced amount of the per-pupil funding that the default public school would get, with the remainder retained by the host district even though the charter school itself provides for itself the services the district would provide for public schools.

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> Charter schools operate as non-default schools within the public school system, they don't get to charge parents at all.

You need a great big asterisk on that statement. There's a well regarded charter school about a mile from my house, we considered sending our kids there. They may not actually charge parents money, but you know what they do? They require parents to spend one day a week volunteering. Technically that isn't a charge, but effectively it's exactly that.

Sounds like they are selecting for families who are heavily invested in their kids' education. Great way to bump the test numbers and have focused classrooms, but it definitely isn't for everyone.

No, they’re investing in people who earn enough that they can take a day off work, or have a single parent earning enough to support them.

Anyone from a family where the parents are necessarily unable to do that cannot attend. So this is a really good way to select for a specific socio-economic group. This also helps inflate grades because most data shows that wealth correlates with academic achievement (for many reasons that aren’t “families are rich because they are smarter than other poorer families”)

You would need to add "charter schools are not allowed to declassify special needs students without a third party evaluation by a public school counselor."

Because that's what they typically do. Special needs students who lag behind but are required to be allowed to attend on vouchers get declassified so that schools no longer have to apply resources towards them. They eventually either fail out and thus are no longer their problem, or are withdrawn by parents.

I too have concerns about charter schools and I suspect that they will end up making the American school system better for a few kinds of families but even more unequal, segregated, and expensive.

However, your assumptions about the motivations of charter school proponents seems uncharitable. The proponents I know come by their position honestly -- they truly believe that vouchers and charter schools are good solutions to the problems facing our nation's students.