First off thank you for the response, though I don't agree with your conclusions I do agree with the spirit of what you have said.
I think the difference is perspective.
Most of the examples of the peaceful experiences you've listed from your time abroad are things that I routinely have experienced throughout my life in the US.
I am now 32 and have lived in here my whole life. During my lifetime the violent crime rate in this country has dropped 30% - 50%, the murder rate has dropped by the same percentage. At the same time the number of news reports covering violent crime has increased by 3000%*
Globally speaking, we live in the single most peaceful and most prosperous time in the history of our species.** Sadly most of us will never understand that, positive news never sells.
My real life experiences run contrary to the constant stream of fearmongering stores we fed by pop culture.
I have lived in both peaceful suburban towns and not so great areas, I also spent a year living in hells kitchen in Manhattan (at the time one of the supposedly bad areas). I have had friends and neighbors of nearly every nationality on earth. I was never scared to walk around any of the places I've lived. Many of these friends and neighbors have also been gun owners, many haven't, they've all been peaceful law abiding US citizens (or residents). Usually the only reason I lock my front door is to stop people from accidently letting my cats escape.
A couple of wreckless drunks at an A.T. shelter isn't going to change my view of the world or make me live in fear.
*Apologies for not having sources immediately available to cite, however these are the numbers that were taught in my college criminology class and are consistant with subsequent reports I have read.
** http://www.bbc.co.uk/news/entertainment-arts-20208505