Security - people generally are not aware of the extent of powers that are at hand (I know I was surprised) for government agencies etc to enable them to protect us all (as well as people such as Queen etc).
It works very well in the backgrounds of our lives and it is meant to be discreet and unknown. The more attention drawn to security issues is highlighting potential vulnerable areas and you won't get someone standing up and explaining exactly why you should trust in the risk assessments on security issues. So you won't know. H&M are acting almost like an enemy within over this issue - they won't get the answers they think they need - as it is meant to be unknown (that's how it works and why it works).
The more they highlight security as an issue it is a self-feeding circle of paranoia and attracting attention. However, if there was a credible threat in the US then the US authorities would have the powers at hand to look into activities and act pre-emptively.
As has been highlighted extremely well by Allington - the real threat is within one's home - women die every week. Other styles of attack do, in fact, take planning and there would be information that would be accessible on such plans and pre-emptive (discreet) precautions would be taken.
But yes dismiss all those very obvious facts and carry on with H&M need a cavalcade every time they drive to the airport.... Edward and Sophie seem to manage just fine popping on holiday etc.
H&M really could lead a quiet, discreet and private etc life - however, they really, really don't want to. They want you to know : TA DA! - they've arrived, we're here!! ie - the opposite of good security....