Through the agency fee, workers in union-represented jobs pay for those services but are shielded from paying for political activities with which they disagree. In those 22 states, the unions are legally bound to represent all workers in jobs under their jurisdiction, even if they aren't members. The fee obviously is a key to unions' performing all their functions, for if it weren't required, many members would quit the union, taking their dues with them and leaving the union without the resources to do its job. That's what union opponents would like to see.

Source: Los Angeles Times February 23, 2018 21:32 UTC