The problem with this, I think, is that people will quickly forget about the bad conditions that created the need for the stipend and only see the people using it for drugs. Politically, this works out to 'unfeasible'. After all, isn't this almost exactly what food stamps are? Technically not a stipend, but they're pretty readily converted to cash on the secondary market.
Australia has the equivalent of a "stipend" for poor, unemployed, students, single parents, etc. Plus free healthcare for everyone. It is a hugely successful program with a very low percentage of exploitation (i.e using the money for drugs, or contributing to unemployment rate). It has been constantly tweaked for the last 20 years. You don't need to look at obscure tribal examples within America, you can just look at…
But you're also wrong about Australia being "a very similar society to the US". Maybe at one time, but Australia has some very authoritarian laws these days - from gun control to internet filters, etc..