That's because your government is totally fucking paranoid. I understand the right to defend one's country, believe me, I get it. 911 was no joke. But when the US government has a serious conversation about putting up a security wall along the Canadian border, all 4000 miles of it, something stinks. There's been a great deal of paranoid misinformation as to what comes into the States thru the northern border, but none of the 911 terrorists did, contrary to what a few of the larger US papers printed, then rescinded.
America is supposed to be "Land of the free, home of the brave." but for a while there it was starting to look like "Berlin Wall : 21st century." Besides, could your enconomy really afford to build the next Great Wall of China in North America?
As for catching terrorists, you've got to throw political correctness out the window, it's not helping. Start by looking in the obvious places.
*political rant off*
That being said, the states is a great place to visit. I've made many friends playing around the Detroit area back when I used to gig, and they've got an amazing Mexican village!
-0z-