Why is there a chiyuv to help these girls? Many Rabbonim have famously paskened that when it comes to children receiving a Jewish education, it is considered dinei nefashos. Indeed, some were even machalel Shabbos to deal with these issues.
If you saw someone drowning, would you say “It’s not my business!” and walk away? You’d be transgressing an issur d’Oraysa in doing so – Lo saamod al daam re’acha!
If a girl doesn’t have a school, it’s considered pikuach nefesh. Everyone who is able to help has an obligation to do so.
As for the Five Towns and high tuition, I can’t speak for all schools, but I can speak about the yeshiva I went to, Darchei Torah. Darchei’s tuition is not cheap. But if someone can’t afford it, they will work with the person to find out what they can afford. I personally know of families who not only paid no tuition at all, but had R’ Bender help them out. I remember when I was in the yeshiva, R’ Bender would meet with every boy before Pesach and find out if they needed a new suit, or a new hat for Yom Tov. If it was needed, he would pay for it.
Yes, tuition is high pretty much everywhere in the US. I just think about it the same way I think about other things. One day, I will be giving a din v’cheshbon, and they may ask me, “How much did you value your children’s Jewish education?” I will be able to answer, “I gave up vacations, a big house, a fancy car, and many other things, and made their education my top priority!” Money all comes from Hashem, and He gives us what we need.