In 1987 Idaho's Right To Work law went into effect. In the years since, the amount of damage it has caused Idaho workers has been castistropic. Right To Work laws have one goal and one goal only. Which is to impact and damage unions, and give big business more power over their workers. Which currently means that employers in the state of idaho are not required to give meal or other kinds of breaks. Idaho aligns with the federal minimum wage of $7.25, and frankly the state of idaho is fairly weak on protections for workers.
According to the 2002 Federal Reserve Bank of St. Louis report (PDF) written by Emin M. Dinlersoz and Rubén Hernández-Murillo, "....the most obvious reason is that the passage of the law makes unions less attractive to workers because unions no longer have the ability to enforce payments and fines. These effects depress new union organizing and also deter the replacement of decertified unions. If a state’s labor force is growing, then less union organizing means also a reduction in the union membership rate."
It's the the strategy of the conservative right to weaken unions with Right To Work laws, and the best way for them to do that is to undermine the financial stability of the unions that are working to protect workers. The best way to do that is to deny the unions the means to campaign and to pay the union officials that are working for the union members.