In my state, all kids in charters must take the state mandated tests, and these are quite specific. It's away beyond what reading and math levels kids have achieved, to extremely specific subject test for every subject. All schools required to take the test MUST teach to the test or they will bomb it. They can call themselves whatever they want, and they can do it as a distance program (if you are in a charter, you are not legally a home schooler but a public school student) but it's all boils down to the same content.
Philosophically, I have a problem with public monies being funneled into "for profit" charter schools. I think all charters should be not for profits and should be regulated as such.
But, honestly, if my best option for kid was a for profit charter, I would take it.
The annual standardized test is a requirement of CA charter schools as well for all students beginning in 2nd grade. In CA though the teachers are not required to teach the test. With the charter school we participated in (that served homeschoolers) we were free to use the resources we chose for our children, and there were many unschoolers in the program as well.
You make a good point though that in a brick and mortar charter school there is likely temptation to teach the upcoming standardized test to students so they will perform well- this is definitely a big criticism of the charters based on non-standardized Ed, such as Waldorf. However, the requirement that charter school students must take the annual standardized test beginning in 2nd grade in CA was imposed by the public school board of CA, not by the charter school movement itself (which pioneered in MN- where charters are granted by the university boards and not by the school districts, unlike CA).