I'm not a fan of an all-charter system, but the arguments need to be more nuanced.
* Not all charters are for-profits. I've started one charter and worked for another, and neither one was for-profit. They were both non-profits that were created in order to try to build a better schooling experience than inner-city kids were currently getting.
* Charters don't necessarily drive down teacher salaries. Both the charter I helped start and the one I worked for paid slightly higher salaries than the nearby public schools (although with fewer job protections)
* Charters don't necessarily mean teacher unions are gone. All of the teachers at the charter school I worked for were still unionized.
* Charters don't necessarily mean lower standards. The rules vary by state - in many cases charters are held to HIGHER standards than public schools, because you can lose your charter if you fall behind on test scores or any number of other areas, while a public school can be messing up in a lot of ways and never face consequences except under extreme circumstances.
* Charters can definitely be cheaper - it depends. For example, public school systems sometimes have a ridiculously high number of administrators - I think I remember there being 3,000 employees in the CENTRAL office for LAUSD - those are 3,000 employees who aren't even working at a school! Very large systems do tend to build fat over time and can be streamlined.
* Charters don't do worse than public schools. There is such a huge variety of charter systems and rules and so many differences between states that you can't accumulate them all like that - some of them do better and some do worse. Ideally, over time the ones that do worse are shut down and the ones that do better are expanded.
There is no easy answer to the question "are charters better or are public schools better"? In Inglewood where I used to live, even the very existence of charter schools was making public schools better, because they were feeling threatened by all the students who were leaving to go to charter schools and began making huge changes in order to try to attract students and their families and keep them in the public system. Ideally, there can be a system with both charters and public schools, and it will be better than a system with only one. The following rules need to be followed though:
1. Charter schools should only be allowed in communities which invite them. In California you need to have a certain # of parents and teachers in a community sign the charter before it can be approved.
2. Charter schools should recieve the same funding as public schools, no more. In fact, this is really "less" funding, as public schools already have infrastructure available that they don't have to pay for, while charters have to start from scratch. In many cases that means charters must input a lot of their own cash or raise funds from outside sources just to get the start-up money to even make the school workable, which discounts the idea that they're in it for the money.
3. Access to charter schools needs to be just as open as access to public schools and they should not be allowed to cherry-pick their student bodies.
4. Charter schools should be held to strict standards and should be closed if they're not meeting those standards. How to evaluate schools in America is of course controversial, it shouldn't come down to mere test scores, but there needs to be a process (of which student/parent satisfaction should really be at the top) by which charters are held accountable.
5. Teacher rights in charter schools should be maintained with strong standards.
6. Public schools should watch successful charters carefully and adopt new practices as their effectiveness is demonstrated.