For one simple reason – it is too big!
A global society was made possible by technologies that spanned the globe easily – electronic communications. These were quickly adapted by business interests to form a global economy – without trying to integrate all the cultures in it.
The result is a global economy that is in perpetual conflict with the many societies in it.
These business interests, however, own the media – that keep telling everyone, that everything is fine – even if millions are starving, or are refugees!
Or it may tell them that these problems are caused by bad people – that must be punished by military means.
But these problems exist on a much smaller scale – inside America itself. Where an Industrial economy is being replaced with a Computer economy – that can employ far fewer people! Many Americans are left out in the cold – and they don’t like it out there!