Many conservatives are innately suspicious of any body wielding worldwide authority. (US military hyperpower is theoretically equally suspect, but since other countries COULD balance us, they just choose not to spend the money, it isn’t such a big deal.)
The problem with worldwide authority is that it loses the constraint of people being able to opt out. If the US becomes a Mormon theocracy, you can move to Mexico. If California goes communist, my in-laws can come to Colorado. If Modesto goes Nazi, they can go to Stockton. When power is local, people can opt out of that power, and that very fact tends to curb abuse of authority - the Temple Police will continue to be powerless outside of Salt Lake City, California can’t afford to go Communist because all the taxpayers will move, and Modesto is too busy creating photogenic sex crimes so they can get on the news to bother with the goosestepping and the bookburning mmmGLAVin.
Whereas if the UN has real power, and chooses to abuse it - where you gonna go? Mars is too cold. That’s one major reason why we hate the UN. The fact that it is a haven for thugs and kleptocrats and has committed more evil than good in its history is relevant, but not the key issue.
Liberals often think of the UN as representing the peoples of the world. Unfortunately, it doesn’t - it represents the GOVERNMENTS of the world. And most governments, most of the time, suck. It’s frankly amazing that the UN hasn’t sucked more.
