The "revolving door" spoken of here isn't quite as simple as it looks. Granted there are problems at "senior government level" but that is rare.

I worked for UK government for a few years. Then I went to the private sector. This happens a lot. Most of people who do, me included, it's because the public sector is so deep in incompetence and stupid politics that it is soul-crushing. Also to get anywhere you tend to have to take placement roles andmove around a lot and resort to a lot of arse licking and back-stabbing. Having a family or any stability is really difficult.

So you leave. And then they attempt to get you back with "enhanced pay" over your initial mediocre salary because there is suddenly a skills vacuum and everything is falling apart. They know who to reach out to because they want people who can slide back in and clean up the mess. All with redundancy again waved around constantly due to government reshuffles.