Or why not execute them instead?
Worked very well for ages ...
More seriously, there usually are no simple solutions to complex problems. And government is a very complex problem. So many people with so many opinions - and everyone involved afraid to say one wrong word or make one wrong decision. I don't think more fear helps there.
I mean - prison for corruption - yes!
But prison for incompetence, no. Then you also have to jail the people who put the incompetent person there in the first place and those people and so on.