Schools are typically paid for out of the property tax which is tied to the local district. That is to say, the local residents pay for the local school. It's not like public schools are paid for by a giant pot of gold in Washington DC.
That's why wealthier areas typically have nicer public schools. Those schools get more tax revenue because the revenue they derive comes directly from the surrounding neighborhoods.
This voucher system and all the talk about bussing kids in from the inner city is just going to upset the apple cart.