And "union dues" isn't even the right term here. In Michigan, for instance, you can work in a union shop without joining the union and paying full union dues. The costs of the union's political activities, its membership events, and more are removed from your dues. You pay a lower fee, because you're just paying, at least in theory, the cost of the union's representation activities.
"Right-to-work" smartly makes it sound like a question of economic freedom. Of course all Americans should have the right-to-work! But as defined by these laws, we don't have that right, or anything close to it. Employer's contracts are full of provisions that employees have to follow in order to work. I didn't have the right to work at the Washington Post without taking a drug test. I didn't have the right to work at MSNBC if I still wanted to appear on other cable news networks. I didn't have the right to work for Bloomberg if I didn't want to deliver a column on the date and at the times it chose.
These contracts govern everything from how employees dress to how they tweet to what gets deducted from their paychecks every week. And if we don't like it, we don't get to just to opt-out of the particular provisions we oppose, as "right-to-work" laws permit you to do with union fees. We have the right to go work somewhere else. But that's about it.
The genius of the "right-to-work" laws is that it makes it seem unusual that you have to agree to follow the terms of the contract that your prospective employers has negotiated with his employees. In fact, what's unusual is that "right-to-work" laws allow you to opt-out of one part of that contract -- the part that your fellow employees have negotiated. You still have to follow all the parts your employer added.
There's a broader question about whether "right-to-work" laws are a good idea. That question is about what they do to wages and to employment and to economies. I'm not trying to answer that question here (though Brad Plumer summed up much of that evidence in this post). No matter where you come down on whether new employees should have to pay into the union that previous employees voted into existence, calling these "right-to-work" laws is misleading and confusing. Passing them does not give anyone "the right to work," at least not as these laws appear to be defining it.