> Bosses don't like unions for a reason and we're supposed to be their bosses.

Because the "Bosses" in your example want to extract the maximum out of a worker, in exchange for giving them the absolute minimum.

But I don't want to treat our teachers that way. I don't think of them as just another resource I can minmax my way through.

Furthermore, I'm not my teacher's boss. They're not a public servant; they're hired by a school board, or a principal. Those folks are either elected, or hired by someone else.

I can see, I guess, the reasoning that I'm the boss of anyone I can vote for - but that chain doesn't just keep going forever.