Unfortunately, it is a thing:
In the last decade, religious organizations have flocked to charter schools as a way to get public tax dollars to promote their private agendas. Sometimes, religious schools simply close at the end of the school year and reopen in the fall as public charter schools, hiring many of the same teachers and taking on most of the same students. By law, these schools should be open and accepting of students of any background and be secular in purpose and in practice. Thematic language and cultural instruction are often the secular justifications for these institutions, although cultural preservation for one particular group of students is clearly the intention. A Greek Orthodox community opens a charter school in Brooklyn with a Greek language and culture theme, with a predominantly Greek staff and clientele; a Florida Jewish school reopens as a Hebrew-theme academy that focuses on Jewish history and culture and teaches the Hebrew language, explicitly serving “Jewish communal purposes.”
Other states don’t mandate that, and often there are no standards within states. Some schools take advantage of that to use slimy tactics to deliberately exclude poor people.
The main mechanic in some schools is a lot of pressure put on the parents to “support their child’s education”, with an unwillingness to volunteer or donate being portrayed as a “lack of commitment”. I know parents at charter schools like that, and while they’re fortunate enough to have time during the day to “volunteer” they’re open about the tactics employed by the administrators.
If your specific school avoids all these issues and the others mentioned, great. But you asked about the general problem, and got valid answers.