The argument is that you benefit from the union whether you are a member or not because you get the same benefits as union members because of the union's bargaining with the management, so you should pay.
I don't really agree with it, but that's the argument.
Dated sept 19,2018
[..]California Gov. Jerry Brown has signed a law that aims to give public employee unions legal cover from potentially expensive lawsuits demanding that they repay certain fees to workers that the Supreme Court in June determined were unconstitutional.
The law, which takes effect immediately, says unions and public agencies cannot be held liable for fees that unions collected before the Supreme Court ruling in Janus vs. AFSCME on June 27 of this year.
That 5-4 court decision ended a 41-year precedent that allowed public sector unions to collect so-called fair share fees from workers who did not choose to join a labor organization but were still represented by a union. The fees often ranged 70 percent to 99 percent of full dues. [..]
>In 24 U.S. states, employees who are working in a unionized shop may be required to contribute towards the cost of representation (such as at disciplinary hearings) if their fellow employees have negotiated a union security clause in their contract with management. Dues are generally 1-2% of pay. However, union members and other workers covered by collective agreements get, on average, a 5-10% wage markup over their nonunionized (or uncovered) counterparts.
>Some states, especially in the south-central and south-eastern regions of the U.S., have outlawed union security clauses; this can cause controversy, as it allows some net beneficiaries of the union contract to avoid paying their portion of the costs of contract negotiation.
>Regardless of state, the Supreme Court has held that the Act prevents a person's union dues from being used without consent to fund political causes that may be opposed to the individual's personal politics. Instead, in states where union security clauses are permitted, such dissenters may elect to pay only the proportion of dues which go directly toward representation of workers.
https://en.wikipedia.org/wiki/Collective_bargaining#United_S...
With Janus, the union that I was recently a member of lost about 1,500/55,000 members. Not a huge impact so far.
Do teachers unions have affiliations with teachers pension funds?
There must be some mutual back scratching going on...surely?
One of the things about unions is that there's really no grand conspiracy... they are quite open about what they want, and getting it generally involves a contract between two parties.