I do not agree that "Combining income redistribution and decentralizing spending would solve poverty today. "

I would argue more individual wealth that's based on

a) cumulative and legal earnings b) penalty-free inheritance c) a system that rewards individual greed d) a system that rewards equal opportunity

would solve poverty today.

For that to work, though -- those have to be world wide rules. Making an individual country as a test ground will not produce repeatable results.

The above also has one more built in assumption -- vast majority of the people are 'good to other human beings' and act 'rationally'.

The definition of 'legal' is of course vague, but must be uniform across the world (not in individual country) and would include things like

a) equivalence of genders/race/religions/ethnic/disability/political/financial/marital/law-enforcement status in the eyes of a law and competitive bidding

b) law of contract

c) uniformly standardized legal language around contracts that does not require legal council to initiate and resolve disputes

e) criminal penalty system that treats qualified threat of a physical or financial harm, with 80% of equivalence to posterior event

(this it to prevent wide spread racketeering )

f) criminal system that requires non-cirmustantial/independently verifiable evidence to result in conviction

g) largely uniform across country criminal law