When people in Germany get their bank accounts seized by the FBI because they bought Cuban Cigars from a shop in Denmark, and it's justified with "US Embargo of Cuba", it becomes easily noticeable that it's not the laws of the UN governing the world.
Instead, more and more, the US is trying to become a world government, with 6.7 billion people affected by their choices, indirectly taxed by their choices (US corps replacing local companies and transporting the profit out of the country), without any representation.
This is a very unbalanced situation, and is just asking for a revolution. Which will end up making life worse for almost everyone.
We need a fair world government if we want to do these things, and that means representation of all people.
Obviously, the US, which would lose the most from this, objects.