In socialism they still work the workers too hard for too little pay and a select group of people tend to benefit. This is because the system you use for economics does not magically remove human opportunistic behavior. Humans as individual or groups will compete and try to get advantages against each other IN ANY SYSTEM. You can make systems you think deter that behavior, but they will constantly look for the loopholes. Humans adapt their greed to any system you give them and training them away from millions of years of opportunistic evolution creating the brain we have today is not something that can happen fast.

In socialism you have unions that unfairly compete and take advantages from one group. In capitalism you have the same thing, the difference I see is just that capitalism is more self regulating where as socialism has to be micromanaged.

You more or less always need a government, so you always have some public power and then you allow private power to operate in a way that requires less overhead and logistics and matches human behavior well.

At the end of the day it's just a system that works will with human behavior, it's not the system that makes humans greedy. We are all born as rather greedy little liars and we are only taught to work within society we have to curb those natural impulses. Kids pretty much all learn to lie on their own and have to be taught to be honest and to share.

The best you can do with socialism is hope that somehow by leveling the fiscal differences between people you would make them less greedy, but I've seen no sign that actually happens. It seems to me people remain greedy and socialism still has all the corruption and greed of capitalism, just usually at much lower quantities because it's less successful/harder to pull off as your main economic system.

That all being said the only real system we see working is where you balance capitalism and socialism in the form of public vs private power, which at the end of the day is a better way to refer to the socialism vs capitalism debate, though reality does clearly show there are no Capitalism nations or Socialism nations, there are just hybrid nations that use both ideas to varying degrees.