Taft-Hartley outlawed closed shops but did not outlaw union shops:
A pre-entry closed shop is a form of union security agreement under which the employer agrees to hire union members only, and employees must remain members of the union at all times in order to remain employed. This is different from a post-entry closed shop (US:union shop), which is an agreement requiring all employees to join the union if they are not already members. In a union shop, the union must accept as a member any person hired by the employer.https://en.wikipedia.org/wiki/Closed_shop
A union shop is a form of a union security clause under which the employer agrees to hire either labor union members or nonmembers but all non-union employees must become union members within a specified period of time or lose their jobshttps://en.wikipedia.org/wiki/Union_shop
A Right to Work law is a state law that outlaws Union Shops in that particular state as well.
A pre-entry closed shop is a form of union security agreement under which the employer agrees to hire union members only, and employees must remain members of the union at all times in order to remain employed. This is different from a post-entry closed shop (US:union shop), which is an agreement requiring all employees to join the union if they are not already members. In a union shop, the union must accept as a member any person hired by the employer. https://en.wikipedia.org/wiki/Closed_shop
A union shop is a form of a union security clause under which the employer agrees to hire either labor union members or nonmembers but all non-union employees must become union members within a specified period of time or lose their jobs https://en.wikipedia.org/wiki/Union_shop
A Right to Work law is a state law that outlaws Union Shops in that particular state as well.