Problem is human greed and ego. Some things sound good on paper but practically completely falls apart when applied to every single person.
So we build walls, enslave eachother and create shitty rules that end up hurting every one of us.
Not to say the world is all shitty because sometimes you get lucky enough to find yourself among people who you can truly let go and collaborate. Then you can bring these walls down and progress together. But it takes time it takes a lot of trust and risk to find these people.