I must be missing a part of your argument.

The parent says that no single technology "solves" the problems of poverty. The biggest strides to improving quality of life measures are made when people are permitted to try to improve their own lives.

Local markets means people from the same economic stratum helping each other. Where do "the rich" enter into it at all? Are you one of "the rich", with a disposable income many times the total income of people suffering from inadequate clean water? Why aren't you "helping"? What would "help" look like, in your vision?