If you don’t have enough to worry your mind, read the NCTQ’s report on teacher pension funding. The unfunded part of pension debt has risen a 100 billion dollars over the last few years.
I had assumed that teacher unions and politicians have basically agreed to promise good teacher pensions without bothering to set aside money to pay for said pensions. Turns out it’s true that money has not been set aside, but it looks like unions had nothing to do with it. I’ve made a little graph of all the states showing unfunded teacher pensions per student (taken from the NCTQ report) against the fraction of teachers unionized (from the School and Staffing Survey).
The scatter is totally random. There’s just no relation there. The politicians may well be responsible. But it’s not the unions.