I like this post from Scott Berkun. (of the Art of PM book)
One habits many managers have is to dump the boring, unpleasant work of their team onto contract workers. The thinking is that full timers deserve the best treatment and contractors are mercenaries: they deserve whatever they get since they won’t be around long.
It’s a mistake - good managers finds a way to treat everyone well. And there are some reasons contractors deserve special attention
I don't think it applies 100% to government contracting, but it does make a lot of sense. Please treat my team well government overlords!