squeak:
As Joseph pointed out, there is no way to enforce a taxation system on non-school parents to fund the “grant” fund (fundraising is what is done currently & does not work), and raising the money is not practical, as you agree.
The only practical method I see to to give incentives to pay full tuitiona and disincentives for non-payment. For example, PTA can have the Rebbe go to the house of full paying parents at a convinent time for them, but non-full paying have to go to school when it is convinent for the rebbe. Extra-cirricular activities (both hebrew & english) only open to full-paying parents, which allow them to cut back on after-school babysitting costs.
In short, those who are poor will be unable to pay no matter what you do, so you may as well convince those on the margins not to ask for a break.
Thank you squeak & Joseph.
concerned mother: We have created a society of handouts. We get it from the Gedolim in EY who say time and again that funding for yeshivos from the govenment is their #1 priority. Those who take in America just follow by taking both from the govenment programs (rather them than others!) and from their fellow Yidden in form of tuition Tzedakka. Who are we to argue?