Just for clarification, right to work does not protect your right to not be forced to join a union in order to hold a job. The implied right not to associate under the 1st Amendment probably protects that, at least as far as state mandated unionization goes. Right to work says if you exercise your right to not join a union, you can likewise not be required to pay protection money to whatever union or collective bargaining unit may represent other workers at your place of employment. In half of the states, there is automatic payroll deductions for costs unions purportedly incur to "represent" non-union employees. So you can't be forced to join a union, or to participate in union activities, or to fund union activities unrelated to general grievance representation under the Constitution. Right to work laws expand worker rights by saying non-union members may not be required to fund ANY union agency fees.
Its not all about "fees or dues"
Right-to-work laws are designed mostly as a power broker over the underclassed poor in the south. Ideal being that the good ole boy system that's common place in the south would be challenged if you allowed unionization. It would give the workers power negations like wages etc...
For example Ive worked for an employer that had a policy that if you attempted or organize work stoppage or start a union you would be terminated. I am not making this up either, weather or not it was enforced is a different story as coworkers did talk about unions all the time. I might also add that this same employer had you sign a " training reimbursement agreement" as they called it . It simply stated you would have to "pay" back training expenses if you resigned or quit before a certain time period, so basically pay to leave. This was easily defeated when challenged in court but still the fact they would even attempt.
Right-to-work in the south has little to do with paying dues its more about power in the hands owners.