Blackbody Radiation vs Swedish Progressive Tax

According to Planck a blackbody of temperature T radiates light of frequency f with intensity (proportional to)

• T f^2 

modulo a cut-off at high frequencies proportional to T. The simple form of Planck's radiation law is motivated in Computational Blackbody Radiation (p 13) as a result of temperature equilibrium with all frequencies (below cut-off) having the same common temperature (T). 

How can such a temperature equilibrium be established? Is there an "invisible hand" arranging this, or is it simply an effect of cut-off? 

To seek an answer let us make a parallel study of the Swedish tax system with the following connections:

• temperature = happiness 
• frequency = income 
• radiation intensity = prestige. 

The Swedish tax system is progressive with a high income cut-off but the prestige increases with the income, maybe quadratically, while all Swedes are just about equally happy. 

How is this Swedish equilibrium established? By an invisible hand making everybody equally happy, or is it simply an effect of the Swedish progressive tax system? Any clue?