Because they have regions in very good circumstances (eg, capital of a small realm) and believe that it's not only acceptable, but normal, for the Lord to sit in his region holding court, doing police/civil work, and surveying the administration constantly. (And consequently, they have very high bureaucracy skills.)
Then they assume that everyone can run tax rates like this, and claim that anyone who's running "only" 18% is a wimp who's obviously just wasting money, because 25% is the tax rate you're "supposed" to be running. 
No one said or believes that.
