Teachers Strike in Chicago

So let me get this straight...

The average teacher salary in Chicago is around $75,000 annually, while the average citizen in Chicago earns around $45,000. And they're out in the streets protesting because they're only going to be getting a four percent raise every year?

The school district is running a budget shortfall of $3 billion over the next three years. And they're upset that there might be cutbacks?

Teachers unions are up in arms because teachers are being asked to be evaluated on merit and performance (just like those of us in the private sector.)  Aren't the students they teach evaluated on merit and performance in the form of grades?

I just don't get it.