Children want things before they learn about money. Socialists believe a government that doesn't give the people what they want is cruel or inefficient. Children believe what they're told. They believe Santa Claus is real and leaders are wise. Socialists believe in the wisdom of their leaders.
Adults are skeptical of leaders, preferring their own wisdom and beliefs.
Children can't imagine human diversity. They assume everyone feels like they do. Socialists think the right plan will make everyone happy. In reality our different values, habits, and perceptions make profound disagreement natural and inevitable. Children need parents who care about them so elected officials claim to care about the people.