Communes work...
(But then again, any group that has like minded goals works.)

Not even that. It doesn't work.

They say that Communism works on small scale like with 20-30 people. But not even that is true.

I mean it either works or it doesn't. And if it does then it should be scaleable. There is no magical threshold to say that Communism works with 30 people but if you add 1 more person then it falls apart.

It's fundamentally flawed. Even marriage is kind of a socialist relationship based on 2 people, and it mostly doesn't work.

There have been studies after studies showing that marriages where there is no common budget ( each spouse controls his own money) work much better. Or there were studies where they shown that couples that sleep in different rooms have a greater sexual attraction to eachother.

So it doesn't even work for 2 people, then how can you scale it up to 7 billion people. It's much much better if things are accounted for, you have money, you have property to count and keep track of the money, that is how it should be done.

I have convinced my wife that we try this, we are already on separate budget, so there won't be a conflict of interest, since the money belongs to who earns it. This doesn mean that we don't share stuff, but fundamentally speaking private property is necessary to manage things better.