Not so. Nonlinear systems are not difficult to control as a rule, with appropriate understanding of servomechanisms. To see how extraordinary such control can be, look at this video:
http://robohub.org/video-throwing-and-catching-an-inverted-p...
> If society/economy/culture is a dynamical system that generates the power-law income distribution and this system cannot dissipate its "energy" and the exponent reaches some critical value then it will collapse or we'll have some kind of catastrophic phase transition.
These things happen, but usually because the system is not fully understood, or there's a reason it isn't being controlled, not because the system is innately uncontrollable. Obviously this moves away from technology and into philosophy, because the question becomes -- not whether the system can be controlled -- but whether such control is consistent with democratic principles.
> I don't think power-law distributions have 2 tails
Of course they do -- for example, any power law rule involving a power that's an even number:
http://i.imgur.com/HU3KZQ7.png
In fact, strictly speaking, all power law distributions have two tails, just not in the same direction:
