Huge disclaimer (and pet peeve): every state has their own definition and requirements for charter schools and there literally is no level of federal consistency. It's important to find out what the laws and requirements are in your state. For example, I teach at a charter school in Oregon. ALL charter schools here are public schools. Publicly funded, not private, not for profit. We can't "pick and choose" only high achieving students. Our rates of students on IEPs are actually above the rest of our district because these students have often fallen through the cracks elsewhere and their parents seek out an alternative. Our class sizes are smaller and we have independence in curriculum choices. We still have to take all the same SBAC assessments that all public schools take.

I don't doubt that there are other places where CS are very different from here, but please stop with the blanket statements that simply don't apply because there is no standard definition.

That is completely false. Charter schools are public schools and can not pick and choose students. They enroll based on a lottery and must adhere to all state and federal mandates.