Given all this teacher-union bashing, it's worth pointing out that conservatives aren't opposed to all public-sector unions. They've embraced the union that represents Immigrations and Customs Enforcement employees, particularly since the union basically declared open revolt against the political leadership at the agency.
Now there's nothing about the ICE union that makes it less vulnerable to conservative complaints about public-sector unions generally, that their interests are sticking the taxpayer with a bill for bigger government. It's just that conservatives are for "bigger government" when it comes to immigration enforcement, no matter how ineffective, and the protests make an enforcement-heavy administration look like a bunch of border doves so the ICE union protests are politically useful.