The have an interest in not being given demerits for using the bathroom (aka: "time off task")
This isn't the 19th century anymore. Unions had served a good purpose, but in no way do they serve the interests of everybody, especially in modern society given labor laws. My experience in several unions only demonstrated how corrupt, inept, and self-serving they are.
We're returning to the 19th century it seems with worker protections being eroded. It makes sense that Unionization would make a comeback.