Mobile bandits and stationary bandits - Leviathan as the least bad

From War! What Is It Good For? by Ian Morris. Page 44.

The Augustuses of this world become rulers by defeating their rivals and keep on ruling because they have more force at their disposal than anyone else. That force, however, has to be paid for. A ruler could just plunder his subjects to pay his troops (the wasteland model), but eventually there will be nothing left to steal. And in any case, as Rome’s worst governors regularly learned, the wretched of the earth will probably revolt long before reaching the point at which everything has been stolen from them.
In the long run, governments only survive if their rulers learn when to stop stealing, and even learn when to give a little back. The economist Mancur Olson made the point nicely by comparing rulers with bandits. Your typical bandit, said Olson, is a rover. He comes into a community, steals everything not nailed down, and rides out again. He doesn’t care how much damage he does; the only important thing is to steal as much as possible and then move on.

Rulers steal from their people too, Olson recognized, but the big difference between Leviathan and the rape-and-pillage kind of bandit is that rulers are stationary bandits. Instead of stealing everything and hightailing it, they stick around. Not only is it in their interest to avoid the mistake of squeezing every last drop from the community; it is also in their interest to do whatever they can to promote their subjects’ prosperity so there will be more for the rulers to take later.

It is normally worth a ruler’s while to spend some money to keep other potential bandits out, since anything a roving bandit steals is something the ruler cannot tax. It makes sense too to suppress violence within the community—murdered subjects cannot serve in the army or pay taxes, and fields laid waste in feuds between villages produce no crops. Even spending royal or aristocratic revenues on roads, harbors, and welfare can start to seem sensible, if the investments yield even bigger payoffs within a tolerable length of time.

Leviathan is a racket, but it may still be the best game in town. Rulers in effect use force to keep the peace and then charge their subjects for the service. The more efficiently the rulers do this, the more profits they reap. Over the generations, competitive pressures nudged the business of Roman government toward more efficient solutions. Allowing tax collectors to steal so much that their victims could not pay the next year’s taxes was bad for business, so Rome stamped it out; letting potentially productive city dwellers starve was even worse, so Rome built harbors and even gave out food for free. Self-interest had the welcome side effect of making the empire’s subjects safer and richer. The paradox of war was hard at work. Men who mastered violence carved out kingdoms, but to run them, they had to turn into managers.