I mainly use Narita these days. It doesn't have any scanners at all except for metal detectors (or didn't; I haven't flown for a couple of years). Security checkpoints are very quick and efficient. The staff seem very competent and quick. Lines are usually short, but even when they're long, things move along very quickly, so there's really no sense of security as being anything more than a minor bottleneck. [This is sort of how security was a long time ago in the U.S.]
In the U.S. airports I usually use, O'hare, JFK, and sometimes other airports for stopovers, things are slow and chaotic. The lines are always huge and move slowly, the required scanner procedure very slow, other rules slow things down (everybody's taking off and putting on their shoes and belts, and despite exhortations to do it in advance, this really bogs things down), and the staff seem to often be inattentive and inefficient.
Where exactly the main problem is, I'm not entirely sure, but I do know that I dread going through security in the U.S. these days...
In the U.S. airports I usually use, O'hare, JFK, and sometimes other airports for stopovers, things are slow and chaotic. The lines are always huge and move slowly, the required scanner procedure very slow, other rules slow things down (everybody's taking off and putting on their shoes and belts, and despite exhortations to do it in advance, this really bogs things down), and the staff seem to often be inattentive and inefficient.
Where exactly the main problem is, I'm not entirely sure, but I do know that I dread going through security in the U.S. these days...