I have increasing distrust for decision-making as the unit gets further away from the individual and family.
Individual - Drink as much soda pop as you like or ban it from your own diet, I don't care.
Family - I have no problem with parental authority to ban soda pop for their children. Some families do, some don't, others restrict it in various ways -- either way, it's not a big deal.
City - Of any level of government, I have the most tolerance for local, city-level decisions. I can live with individual cities deciding whether they want to welcome fast food restaurants or not -- and many already do.
State - Would strongly oppose a soda pop size restriction.
Nation - Don't tell me what I can or can't put into my body.
United Nations - Can you imagine the UN trying to ban the size of soda pop? Laughable.
The city -- or city-state -- is actually the best place for experimentation with rule systems. Just look at Hong Kong or Singapore. I'm looking forward to more free cities when they get off the ground in Honduras. The city-state is where most of the innovation should take place, because they're easy to leave if people don't like the rules.