[vkou]

They only keep their jobs through the administrations when they do as they are told. If the president wants to change a department's policy, and the department pushes back, he can fire as many directors as he needs to.

[ceejayoz]

There are quite a few protections for the civil service rank and file.

https://www.vox.com/2018/8/27/17786324/trump-fires-governmen...

> The reason he can’t is simple: Unlike his employees at the Trump Organization, about a third of federal workers belong to unions. And those unions have negotiated certain job protections for workers, which includes a process that gives workers a chance to improve their job performance before they are terminated.

[vkou]

You don't fire the line workers, you fire the managers. Workers don't set policy. They do what they are told.

None of the directors, or the senior administrators setting policy are unionized.