That's because these programs start with idea of having societal benefits but eventually persist to serve themselves (and the people they employ). Elevating people out of your program makes the peogram less necessary (along with the voters it employs).
The Government Program Industrial Complex, if you will.
The compromise between those two ideas is what we have today.
His thinking was that he didn't have a birth certificate, had no idea where it was, and he was WORRIED that if he brought this to the government's attention he could be declared a "non-citizen" and might be...well..he didn't really know. He was very fearful of this.
Eventually he found a girlfriend who was a friend of mine and we convinced him to sort out the situation and everything worked out just fine (he was obviously NOT the first person in Canada with this situation). But imagine he had gone for all these years avoiding the government just because of this line of thinking. So there is something to your point here about the fear of bureaucracy and scrutinization.
Because if the problem goes away those people won't have reasons to vote for you next time around. LBJ has some choice quotes about this concept, it's not a new thing.
Separate thought: with so much focus on the oppressed and downtrodden in our politics these days, how is it that obvious problems like the parent commenter mentions are not being fixed?
Why aren't reasonable people of both parties trying to create the right incentive structures for the poor at least in areas where they both agree?