First and foremost, charter schools are public schools. They are funded by the same tax dollars as are "traditional" public schools. Those funds are allocated on a per-student-enrolled basis, as well. And, like "traditional" public schools, to be eligible for those funds charter schools must adhere to all state and federal laws governing public education. Charter schools cannot charge tuition or set admission standards, and they must be non-sectarian in all activities.
However, to encourage innovation in faculty development, curriculum development, pedagogy, administration and governance, and performance assessment, charter schools are free from many state and local regulations that traditional public school districts must follow.
Although still public schools, most charter schools are operated not by traditional public school districts but by independent, non-profit (501c-3) school boards of trustees. The school boards are responsible for oversight of all school operations. Those boards are, in turn, responsible to their "sponsors" (see "What is a Charter School Sponsor?").
Charter Schools Cannot Charge Tuition
Like all public schools, charter schools are free to all students. The only fees that can be charged are those that "traditional" public schools may also charge per state law.
Charter Schools Cannot Set Admission Requirements
Charter schools are prohibited by law from requiring any sort of admission test, or setting any sort of admission requirement. Charter schools absolutely cannot "take the cream of the crop" -- the students with top academic backgrounds, artistic backgrounds, etc. By law, all charter schools must accept whoever requests to enroll, regardless of academic ability, disability status, etc. The only public schools in Missouri with the authority to set admission standards and accept only "top-notch" students are District-operated magnet schools.
Charter schools may establish geographic boundaries from which to accept students -- similar to the school boundaries established by "traditional" schools comprising a multi-school district. But unlike "traditional" public schools, charter schools can establish such boundaries only if "such preferences do not result in the establishment of racially or socioeconomically isolated schools and provided such preferences conform to policies and guidelines established by the state board of education" (RSMo 160-410). This legal restriction is a safeguard against any sort of enrollment profiling.
Per state law, once maximum enrollment at a school is met, all additional applicants are placed on a waiting list; when a seat opens up, a student on the waiting list is chosen by lottery, so all on the list have an equal chance of gaining that seat (as with "traditional" public schools, exceptions for siblings of currently-enrolled students apply).
Charter schools must provide special education and ESL instruction and services, just as all other public schools are required to do.