That would mean we would have to rearrange distribution of resources, so that everyone would have everything provided in equal amounts. This means taking significant amount of wealth from the rich north to provide it to the poor south. You’d also have to move people from their places so that the whole planet’s surface would be inhabited in equal density and thus solve the overpopulation problem (if not, it would mean you’d send more help to certain areas than in some other places that have less inhabitants) It would also have to include dealing with crime and corruption. which is complicated in only one country, much less in all of them together. So, how to make this possible?
You’d have to set up one world government, or make all governments in the world identical. In that case,all people would be forced by law to participate in this. That is impossible not only politically, but also because well, humans simply don’t want to live under the same roof and behave the same way. I won’t even start on why would everyone oppose this concept without second thought. So, how to make people accept this?
You’d have to change their ideologies and mindset. You’d have to set up an ideology which would be some mix of communism and minimalism. Communism because everyone would have to have it equal (no caste, no class, no societal differences that would make two people live under different conditions because then, the whole concept of providing necessities to everyone would fall flat) and minimalism (because the number of people is growing, and the amount of resources is lessening, so people would have to ditch consumerism and adhere to live with only what they need). Speaking of that, the whole idea would sooner or later need some sort of population control that would make people have less children and thus less people to take care of (think of X number of children policy). It would be easier to provide everyone with everything if there are less people to manage.
Now my brainstorm is closing to an end, so I’m running out of ideas, but if we want to create a utopia, we’d need to drastically change humanity. It would probably affect the very concept of culture, politics, national/ethnical identity, economics, warfare (as you know, wars are happening all the time, which greatly affects the possibility of providing everyone with what they need), morality itself, and probably many other things.
You’d have to create Utopia, and that is so difficult it may as well be called impossible.
Not to mention how to manage this system and keep it afloat if it ever gets established.