How can your limited experience make any claims about the government workforce as a whole.

It requires a decent amount of time to understand if someone is talented and that talent is being used to better their job.

>but is doing exactly what they want to do with their life in a role that generates measurable utility for the taxpayer is not packing up and leaving

How would you know? Some people have very strong convictions and as another comment stated if a person is talented it increases the chances they could find another job similar to their desired work