Most of the critical reviews are by fanboys. For the most part they're right about the silly premise. If you're in the business of saving the world/galaxy/universe, you are the competent governing authority philosophically, morally, legally. By what right can the UN claim authority? They have no mandate or competence to deal with such tasks. Many of their members are illegitimate or obsolete shells. The US isn't really a country anymore than the EU is. Feudalism 2.0 has landed in the West with both feet. With geography being much less important to the wielding of power than feudalism's first go round. Then we're treated to Vision's brilliant theory that since the number of heroes has increased that's responsible for the increase in super villains and ET invasions. Now you could have had realistic premise for an internecine conflict. The Avengers stage a false flag attack to raise money for their retirement. Ironically that's what this movie is really about anyway.