I guess I would have to first look through the history of religious education that has been integrated with general charter based education, and when tax dollars were first initiated through a voucher system to support these religious themed schools in order to answer that question.
I do see what you’re trying to get at since separation of church and state is a primary focus. The endevor to keep the nation unbiased and neutral in that regard should stay on people’s minds for clear reasons to keep religious influences from affecting others in negitive ways.