Because, we can't trust poor people to make good decisions. Otherwise, we'd empower them rather than clean up after them. Given that we have enough money to not be living hand to mouth, we make better decisions.

That was sarcasm.

Best piece I've come across on this topic, with applications even past development aid into social aid and other issues, is: https://www.ted.com/talks/ernesto_sirolli_want_to_help_someo...