How school funding currently works:
A long time ago, it was written into the Texas Constitution that ISD property taxes could only fund education.
John pays property taxes, the ISD portion is average $6k-$7k. The ISD collects property taxes from everyone in their district boundaries. Then the state has a calculation that is Property Tax Revenue/Weighted Average Daily Attendance. If this revenue is too high, the ISD sends back a portion to the state. This portion goes into the Foundation School Program fund. If this revenue is too low, the state sends back a portion of the Foundation School Program fund to the ISD.
In addition to property taxes, state lottery, state general fund, federal dollars, and local bonds all make up education funding. Most districts spends about $9,000/per student. $6,160 of that is the basic allotment for 100% perfect attendance and comes from the property taxes. The districts that quote $14k-$16k per student are usually including bonds and federal free lunch dollars. Both bonds and federal free lunch dollars have very specific things they can be spent on.
Currently, the state has cut its contributions from state lottery and state general fund because the property taxes recaptured from property rich ISDs is very high and daily attendance has been lower during and after COVID. So the state has grown its surplus over the past 5 years on the backs of education.
Right now, what's draining money out of the Foundation School Program fund is charter schools. They are only given the basic allotment of $6,160 and some federal dollars depending on what they offer. They don't get bonds and usually aren't eligible for other state funds. If there was no recapture, Texas probably couldn't pay for charter schools. (Now with the voucher program, I do think most charter schools would be reimagined into private schools).
Basic allotment hasn't grown since 2019, even with the addition of several bills in the last couple of sessions that come with required spending and safety upgrades. Some could be bonds, some couldn't. Teachers also want a raise to keep up with inflation and the rise in housing/groceries/utilities.
Now to vouchers - the last couple of bills have floated $10,000 per kid to go to private school or homeschool. Let's say John has 3 kids. He has paid in $6,000 to get back $30,000. $10,000 is more than most public schools get per student, especially when all $10,000 is allowed to be spent freely by the private school or homeschool. The vouchers would be paid first out of anything left in the Foundation School Program fund, then out of the surplus. When both are depleted, there is no additional funding generator. This is why there are limits to the voucher program.
If the voucher program is limited, who is receiving it? How do families know if they are going to receive it? Do you apply and get accepted by a private school, then wait to apply for the voucher, then hopefully be awarded the voucher to pay for the private school. If you are poor, are you going to jump through all those hoops for "maybe"? What if you don't get awarded the voucher and you can't afford it? Thus the ones that will apply for the vouchers and be awarded the vouchers are mostly middle class to upper class families already interested in private school.
Now let's swing back to recapture being a formula of property tax value/weighted average daily attendance. As students who attend the district drop because of vouchers, the likelihood the ISD will become a recapture paying district increases. For some rural counties, we may be only talking 25-50 students that could swing them from property poor to property rich - these are also kids who probably wouldn't go to private school but would be homeschooled.
Currently, there are no restrictions on private schools. They don't have to follow TEKS. They don't have to pass the STAAR. They don't have to hire certified teachers. They don't have to offer PE, offer Recess, offer art & music, have a cafeteria, or teach violent SPED kids. Learning disabilities need not apply. Who care about safety, there's no police officer, single entry, raptor program that the private school has to fund - these are all requirements of a public school by law.
Eventually with the vouchers, the thought is that public schools won't become more like private schools but private schools will become more like public schools as pressure for equality is put on the voucher program.
Now, I don't think vouchers are inherently evil anymore, but they need to be part of a completely overhauled system. The only proposals I've seen around vouchers deal with drawing money out of the property tax system to line pockets that it was never supposed to line. Until the state pays back all the lottery money and general fund money that it's drained from the system, I have no faith they actually want to do right by education in Texas.