Because one is the government and the other isn't. That's my whole point about it being reasonable that this is a Constitutional issue.

There's also the, arguably separate, issues of incentives and who ultimately pays. In the case of private employers, it is, presumably a powerful few trying to exploit the labor of the many. In the case of government, it's the taxpayer/voter who is ultimately being bargained "against".

What are public employee unions trying to prevent? The exploitation by the many (voters) of the labor of the few? That seems wholly unreasonable to me.

> Why shouldn’t a union be political? Don’t workers have a right to gather in a group and be political? Government workers should be excluded from this activity?

(Again, not a union, but a public employee union:)

Because they are, in effect, circumventing the normal political process. By using the power to strike, they're seizing power from the voters.

> Why shouldn’t a union be political?

By that argument, why shouldn't the government force you to donate money to political advocacy groups that it chooses, whether or not you support the group's agenda?

Heck, what if your employer decided that a portion of your paycheck would be deducted as a mandatory donation to either the Democratic or Republican party, as part of the terms of your employment?