When Labor Day became a federal holiday in 1894, government employees weren’t allowed to unionize. Now, they make up almost half of all union members. This would be unacceptable, even if they were all showing up to work. But they are not, and that adds insult to injury. President Joe Biden needs to make sure they do. Just 10% of wage earners are members of a union, down from more than 30% in the 1950s. The number is still falling. However, the percentage of public sector workers who belong to unions is much higher, at 33%, and rising. Some 7.1...