To a certain extent, America does do a great deal of trendsetting, though mainly in the world of pop-culture. Outside of this and the examples that you used, certainly they weren't "trends" set by America, but many of them would also hardly be qualified as trends.
While there is plenty of truth in the fact that you likely thought it was "only in America", this is still hardly anything to even speak remotely lightly of. School shootings are still quite a bit of a rarity in this country and the main reason anybody really knows about them is because our media takes this terrible topic and turns it into a ratings machine, constantly spinning stories about why the person did it.
Your edging around straight-out calling me a cloud-viewed patriot lacking an ability to see the bigger picture is far from true. While I'm proud of my country and the many great accomplishments it has achieved, I know America falls short in many areas and should look to Europe and other places for several examples of what they should be doing. America is not somehow better than the rest of the world (though certainly parts of it...I'm not afraid to say I don't support the dictatorships of North Korea and the like) and many Americans see that - traveling to Europe two summers ago, I made sure to respect the culture in the cities and places I visited, I spoke as much German as I possibly could (and the Germans would extremely gracious and many would switch to English if I was having an difficulty without my prompting) and admired many things about European way of life. I saw things from their point of view, asked them questions, found out many things, and it helped me shape a better world-view I still cherish to this day. That is hardly the personality and beliefs of a cloud minded patriot.
I believe there is a group just as bad as the "stupid American" (they exist, though they're oftentimes portrayed a little over the top in my experience)...and it's "blindly blame America" people (and YES, I know there are things American is to be blamed for...this is NOT what I am referring to when talking about these people). These people don't necessarily hate America or Americans, but use America's powerful position as a way to blame them for world problems, mock them (too many times have I seen online the rantings of a European who thinks all Americans are fat, sloppy, uneducated hicks who want to control the rest of the world, hate the environment, and are somehow a lesser people because many speak only one language fluently), and generally look down upon them. This is disgraceful and there would be an uproar if it were the opposite way around. I love the differences in the European culture...I wish America would embrace many of them (especially things like more people living in cities and commuting in smaller cars, taking public transportation, etc) and I have a great interest in the world-community as a whole. Call me a cloud minded patriot, but if you do, it shows you lack the ability to accurately judge me.