It's a perfect example of dispersed costs and concentrated benefits. The public school contractors and employees who benefit from the taxpayer-financed bonds have a huge incentive to push voters to approve them. Average property taxpayers won't notice a big difference, so they don't have much incentive to organize against the bonds.
But over time, it adds up. Austin ISD currently spends over $100 million a year on debt service.
Texas public schools have way too much money at their disposal. As long as we have public schools, that's how it will be. Libertarians support ending government financing and control of schools.