There's an entire genre where the American president is an attractive badass who starts gunning down terrorists or aliens the moment his country needs him to. In one movie, the president's home is referred to as the home of the Gods. If we weren't already familiar with the genre, a strong and sexy leader killing all his enemies to inspire his people would sound like a movie Kim Jong-il demanded be made by the filmmakers he kidnapped. Even in the many movies that feature an evil congressman or senator, the president is beyond reproach.
Other western democracies don't have an equivalent of this. Benedict Cumberbatch isn't going to shoot all the terrorists who have occupied 10 Downing Street. There are no Canadian films about a ripped Will Arnett saving 24 Sussex Drive from aliens. In London Has Fallen, the American president kicks some ass while the assassination of the British PM triggers the plot and the leaders of Canada, Germany, Italy, France, and Japan are unceremoniously blown up by terrorists. The American President is a mythical figure who destroys anyone who dares to f**k with him, while the leaders of other countries are expendable plot devices barely worthy of mention unless it's to fuel President Aaron Eckhart's righteous vengeance.
London Has Fallen is an extremely stupid movie that inadvertently sums up how America sees itself and its president -- as the action-movie hero who needs to save the world. London's Metropolitan Police, who in real life just stopped a terror attack within minutes, are tricked by the terrorists, slaughtered, then pulled back to wait for America to save their own city. It's a powerful fantasy, except in reality the guy currently playing the lead role is more fit to star in Paul Blart: Mall Cop than Independence Day, and Americans are struggling to wrap their heads around that.
In my time visiting America, absorbing American news and pop culture, talking to my American friends and colleagues, and pretending to be a cute American teen in online games to extort virtual money and items from lonely Chinese boys, there are two common beliefs I've seen everywhere. The first is that the modern American government is a necessary evil that cannot be trusted. Even Americans who support, say, an increased government role in healthcare, love to grumble about other aspects of the government. Extreme advocates of "big" government in America would be boring moderates in Europe.