You need cause to fire a federal employee, and that requires documentation. You often need to put them on a PIP first, giving them a chance to correct and avoid

You need cause to fire a federal employee, and that requires documentation. You often need to put them on a PIP first, giving them a chance to correct and avoid being fired. If they do something that can cause them to lose their clearance you can fast track this a bit, because the ability to maintain a clearance is part of their job requirements. But this also requires supervisors willing to actually supervise. Often these folks just get shuffled around, they know no one wants them, but they know no one will go through the trouble of firing them either. Shameless, worthless people will happily suffer that indignity for years if they're also getting a low six-figure salary and know they'd get $0 outside of government because private companies would fire them with cause and they'd stop getting any salary.