Bottom decile personal income in U.S. is above $5,000 which puts people in that bracket above the median person in Mexico and not terrible far below the median person in Poland: http://super-economy.blogspot.com/2010/04/median-earnings-hi... (note the chart is in PPP-adjusted dollars).
Poverty in the U.S. means subsidized housing, terrible schools, food stamps, etc. But survival is guaranteed.
So the issue with basic income is not eliminating poverty. It's about changing the mechanism by which we have eliminated poverty.