Conor Clarke gets at a really fundamental issue. One's political views depend in part on one's view of human nature.
In my view, people on the left slip too easily into the implicit assumption that the move from business to government somehow cleanses people of their selfishness and irrationality. With this magic cleansing of individual frailty, government will be wise and benevolent, as opposed to the greedy and mistake-prone private sector.
In my view, humans naturally compete for status.
For example, if you look at the salary structure in a corporation, you may see greed. There is that, but there is also what I would call a male dominance hierarchy, with salary constituting an important indicator of one's place in that hierarchy...
If you look at politics, you may see good guys and bad guys, and you vote for the good guys. There is that, but there is also a male dominance hierarchy.
This is clearly a controversial topic. One of my daughters is taking an introductory anthropology course that seems to me to be taught from a very left-wing perspective. The professor seems to believe that social inequality is an artificial product of modern (post hunter-gatherer) societies. Obviously, I disagree. I believe that our species has been competitive from the ape stage onward. But I am not a professional anthropologist.
I tend to be quite wary of anthropologists who claim that tribal humans lack sexual jealousy or are peaceful or are non-hierarchical. My daughter is being taught that primitive people are egalitarian, and I wonder in what sense that is actually true.
I suspect that to the extent that humans are egalitarian, this emerges less in a willingness to give to the poor than in a willingness to steal from the rich. I have to make a sacrifice in order to give to someone who is poor. I have to sacrifice less in order to steal from someone who is rich. I have to sacrifice even less by posturing in favor of equality.