As someone who worked for the Federal Government (DOD), I saw people who were clearly unemployable anywhere else. Alcoholics, do-nothings, EEO hires, and many more unfirables. One woman I worked with was off the job for six months, due to her alcohol addiction. She didn't get fired, and came back to her job, which someone else did very competently in her absence. Same job, same sloppy work, but she was protected.