Well, most important is how inefficient the country is. All governments are corrupt: thats true in Europe, its true in Canada, but its 10x true in the US. It's no China or Russia, but its pretty bad.
Second, you said "resistance to supporting your own people". Well, even if you don't resist, thats very difficult because figuring out who "your own people" is, is nearly impossible here because of the immigration situation.
Regardless of stance on immigration, the fact is that the way to most efficiently reduce poverty will differ based on if someone has been here all along and got screwed, based on if they are refugees, or if they came by other means. You have to analyze the pipeline and allocate resources, people, and programs for both prevention, and for safety nets.
People make it so damn hard to differentiate and allocate logically, its impossible to be efficient there.
(Note that I'm a green card holder, I wasn't born in the US, so this is just what I'm seeing in polar contrast to my home country). When data is collected and surveys/analysis presented, most of the time everything will be mixed in without separating root causes (someone who fell into poverty because of medical bills, is a very different problem to solve than someone who came here being poor in the first place). And then there's the racism situation...
So authorities are left with 1 size fit all programs that get abused left and right, with corruption sprinkled in to make it harder. Yeah, its impossible to fix things this way.