Unions are nonprofit, they don't exist to "extract money" from anybody. They exist to act on the behalf of all their members in negotiations, to increase wages

Unions are nonprofit, they don't exist to "extract money" from anybody. They exist to act on the behalf of all their members in negotiations, to increase wages and to provide employment-related services like labor lawyers in case of a wrongful firing. In the airline industry, Union workers make on average $12k more than non-union workers, which more than makes up for the $700 dues.